MECHANICS OF THE HOUSEHOLD 



Tke QmwJ/ii/ Book (xx 7m 

PUBLISHERS OF BOOKS F O R^ 

Coal Age ^ Electric Railway Journal 
Electrical World v Engineering News-Record 
American Machinist v jhe Contractor 
Engineering 8 Mining Journal ^ Po we r 
Metallurgical 6 Chemical Engineering 
Electrical Merchandising 



MECHANICS 



OF THE 



HOUSEHOLD 



A COURSE OF STUDY DEVOTED TO 

DOMESTIC MACHINERY AND 

HOUSEHOLD MECHANICAL 

APPLIANCES 



E. S. KEENE 

DEAN OF MECHANIC ARTS 
NORTH DAKOTA AGRICULTURAL COLLEGE 



First Edition 



McGRAW-HILL BOOK COMPANY, Inc. 
239 WEST 39TH STREET. NEW YORK 

LONDON: HILL PUBLISHING CO., Ltd. 

6 & 8 BOUVERIE ST.. E. C. 
1918 



Copyright, 1918, by the 
McGraw-Hill Book Company, Inc. 



APR -8 1918 



THEM jLi P LE PRESS YORK PA 

oL ©CI.A494481 



INTRODUCTION 

This book is intended to be a presentation of the physical 
principles and mechanism employed in the equipment that has 
been developed for domestic convenience. Its aim is to provide 
information relative to the general practice of domestic engi- 
neering. The scope of the work is such as to present : first, the 
use of household mechanical appliances; second, the principles 
involved and the mechanism employed. It is not exhaustive, 
neither does it touch many of the secondary topics that might be 
discussed in connection with the various subjects. It does, 
however, describe at least one representative piece of each type 
of household apparatus that is used in good practice. 

The mechanism used in the equipment of a modern dwelling 
is worthy of greater attention, as a course of study, than it 
has been heretofore accorded. The fact that any house, rural 
or urban, may be provided with all domestic conveniences in- 
cluded in: furnace heating, mechanical temperature regulation, 
lighting facilities, water supply, sewage disposal and other 
appliances, indicates the general use of domestic machinery in 
great variety. To comprehend the application and adapta- 
bility of this mechanism requires a knowledge of its general plan 
of construction and principles of operation. 

Heating systems in great variety utilize steam, hot water, 
or hot air as the vehicle of transfer of heat from the furnace, 
throughout the house. Each of these is made in the form of 
special heating plants that may be adapted, in some special 
advantage to the various conditions of use. A knowledge of 
their working principles and general mechanical arrangement 
furnishes a fund of information that is of every day application. 

The systems available for household water distribution take 
advantage of natural laws, which aided by suitable mechanical 
devices and conveniently arranged systems of pipes, provide 
water-supply plants to satisfy any condition of service. They 
may be of simple form, to suit a cottage, or elaborated to the 
requirements of large residences and made entirely automatic in 



vi INTRODUCTORY 

action. In each, the apparatus consists of parts that perform 
definite functions. The parts may be obtained from different 
makers and assembled as a working unit or the plant may be pur- 
chased complete as some special system of water supply. An ac- 
quaintance with domestic water supply apparatus may be of serv- 
ice in every condition of life. 

The type of illumination for a house or a group of buildings, 
may be selected from a variety of lighting systems. In rural 
homes, choice may be made between oil gas, gasolene, acetylene 
and electricity, each of which is used in a number of successful 
plants that differ only in the mechanism employed. 

Any building arranged with toilet, kitchen and laundry con- 
veniences must be provided with some form of sewage disposal. 
Private disposal plants are made to meet many conditions of serv- 
ice. The mechanical construction and principles of operation 
are not difficult to comprehend and their adaptation to a given 
service is only an intelligent conception of the possible con- 
ditions of disposal, dependent on the natural surroundings. 

There are few communities where household equipment can- 
not be found to illustrate each of the subjects discussed. Most 
modern school houses are equipped for automatic control of 
temperature, ventilation and humidity. They are further 
provided with systems of gas, water and electric distribution 
and arrangements for sewage disposal. These facilities fur- 
nish demonstration apparatus that are also examples of their appli- 
cation. Additional examples of the various forms of plumbing 
and pipe fittings, valves, traps and water fixtures may be found 
in the shop of dealers in plumbers and steam-fitters supplies. 

Attention is called to the value of observing houses in process 
of construction and the means employed for the placement of 
the pipes for the sewer, gas, water, electric conduits, etc. These 
are generally located by direction of the specifications provided 
by the architect but observation of their installation is nec- 
essary for a comprehension of actual working conditions. It 
is suggested that the work be made that of, first, acquiring 
an idea of established practice, and second, that of investigating 
the examples of its application. 



CONTENTS 

Preface v 

CHAPTER I 

Page 

The Steam Heating Plant 1 

Heat of Vaporization — Steam Temperature — Gage Pressure — 
Absolute Pressure — Two-pipe System — Separate-return System — 
Overhead or Drop System — Water-filled Radiators — Air Vents — 
Automatic Air Vents — Steam Radiator Valves — The House-heat- 
ing Steam Boiler — Boiler Trimmings — The Water Column — The 
Steam Gage — The Safety Valve — The Draft Regulator — Rule for 
Proportioning Radiators — Proportioning the Size of Mains — Forms 
of Radiators — Radiator Finishings — PipeCoverings — Vapor-sys- 
tem Heating. 

CHAPTER II 

The Hot-water Heating Plant 37 

The Low-pressure Hot-water System — The High-pressure Hot- 
water System — Heating-plant Design — Overhead System of Hot- 
water Heating — Expansion Tanks — Radiator Connection — Hot- 
water Radiators — Hot-water Radiator Valves — Air Vents — Auto- 
matic Hot-water Air Vents. 

CHAPTER III 

The Hot-air Furnace 51 

Construction — Furnace-gas Leaks — ^Location of the Furnace — 
Flues — Combination Hot-air and Hot-water Heater. 

CHAPTER IV 

Temperature Regulation 59 

Hand Regulation — Damper Regulator for Steam Boiler — Damper 
Regulators for Hot-water Furnaces — The Thermostat Motor — 
Combined Thermostat and Damper Regulator — Thermostat-motor 
Connections. 

vii 



viii CONTENTS 

CHAPTER V 

Page 

Management of Heating Plants 70 

General Advice — The Economy of Good Draft — General Firing 
Rules — Weather and Time of Day — Night Firing — First-day 
Firing — Other Day Firing — Economy and Fuels — For Burning Soft 
Coal — For Burning Coke — Other Rules for Water Boilers — Air- 
vent Valves on Radiators — The Air Valves — End of the Season- — 
The Right Chimney Flue — ''Smokey" Chimneys. 

CHAPTER VI 

Plumbing 82 

Water Supply — Water Cocks — Bibb-cocks — Self-closing Bibbs — 
Lever-handle Bibbs — Fuller Cocks — Wash-tray Bibbs — Basin 
Cocks — Pantry Cocks — Sill Cocks — Valves — Kitchen and Laun- 
dry Fixtures — The Bathroom — Bath Tubs — Wash Stands and 
Lavatories — Traps — Back-venting — Soil Pipe — Water Closets — 
Washout Closets — Washdown Closets — Siphon-jet Closet — Flush 
Tanks — ^Low-down Flush Tank — Opening Stopped Pipes — Sewer 
Gas — Range Boilers — The Water-back — Excessive Pressure — 
Blow-off Cock — ^Location of Range Boiler — Double Heater Con- 
nections — Horizontal Range Boilers — Tank Heaters — Overheater 
Water — Furnace Hot-water Heaters — Instantaneous Heaters. 

CHAPTER VII 

Water Supply 125 

Water Analysis — Pokegama Water — River Water — Artesian Water 
— Medical Water — Organic Matter — Ammonia — Hardness in 
Water — Iron in Water — Water Softening With Hydrated Sihcates 
— Chlorine — Polluted Water — Pollution of WeUs — Safe Distance 
in the Location of Wells — Surface Pollution of Wells — Water 
Table— The Divining Rod— Selection of a Type of Well- 
Flowing Wells — Construction of Wells — Dug Wells — Open Wells — 
The Ideal Well — Coverings of Concrete — Artesian Wells — Driven 
Wells — Bored Wells — Cleaning Wells — Gases in Wells — Pecu- 
harities of Wells — Breathing Well — Freezing Wells — Pumps^- 
The Lift Pump— The Force Pump— Tank Pump— Well Pumps 
— Wooden Pump — Pumps for Driven Wells — Deep-well Pumps 
— Tubular Well Cylinders — Chain Pumps — Rain Water Cisterns — 
Filters — The Hydraulic Ram — Single-acting HydrauUc Ram — ■ 
The Double-acting Hydraulic Ram — Domestic Water-supply 
Plants — Gravity Water Supply — Pressure-tank System of Water 
Supply — The Pressure Tank — Power Water-supply Plants — 
Electric Power Water Supply — The Water Lift. 



CONTENTS ix 

CHAPTER VIII 

Page 

Sewage Disposal 168 

The Septic Tank— The Septic Tank With a Sand-bed Filter— 
The Septic Tank and Anaerobic Filter — ^Limit of Efficiency. 

CHAPTER IX 

Coal 182 

Oxidation of Hydrocarbons — Graphitic Anthracite — Cannel Coal — 
Lignite — Peat — Wood — Charcoal — Coke — Gas-coke — Briquettes 
— Comparative Value of Coal to Other Fuels — Price of Coal. 

CHAPTER X 

Atmospheric Humidity. . 196 

Humidity of the Air — Relative Humidity — The Hygrometer — The 
Hygrodeik — Dial Hygrometers — The Swiss Cottage ''Barometer'' 
— Dew-point — To Determine the Dew-point — Frost Prediction — 
Prevention of Frost — Humidifying Apparatus. 

CHAPTER XI 

Ventilation 219 

Quantity of Air Discharged by a Flue — Cost of Ventilation — The 
Wolpert Air Tester — Pneumatic Temperature Regulation — 
Mechanical Ventilation — The Plenum Method — Ventilation Ap- 
paratus — Air Conditioning — Humidifying Plants — Vaporization 
as a Cooling Agent — Air-cooling Plants — Humidity Control. 

CHAPTER XII 

Gaseous and Liquid Fuels 250 

Gaseous and Liquid Fuels — Coal Gas — All-oil Water Gas — Pintsch 
|Gas — Blau Gas — Water Gas — Measurement of Gas — Gas Meters 
How to Read the Index — Prepayment Meters — Gas-service Rules — 
Gas Ranges — ^Lighting and Heating with Gasoline — Gasoline — 
Kerosene — The Cold-process Gas Machine — The Hollow-wire Sj^s- 
tem of Gasoline Lighting and Heating — Mantle Gas Lamps — 
Open-flame Gas Burners — The Inverted-mantle Gasoline Lamp — 
Portable Gasoline Lamp — Central Generator Plants — Central- 
generator Gas Lamps — Boulevard Lamps — Gasoline Sad Irons — 
Alcohol Sad Irons — Alcohol Table Stoves — Danger from Gaseous 
and Liquid Fuels — Acetylene-gas Machine — T3^pes of Acetylene 
Generators — Gas Lighters — Acetylene Stoves. 



X CONTENTS 

CHAPTER XIII 

Page 

Electricity 305 

Incandescent Electric Lamps — The Mazda Lamp — Candlepower 
— ^Lamp Labels — Illumination — The Foot-candle — The Lumen — 
Reflectors — Choice of Reflector — ^Lamp Transformers — Units of 
Electrical Measurements — Miniature Lamps — Effects of Voltage 
Variations — Turn-down Electric Lamps — The Dim-a-lite — Gas- 
filled Lamps — Dayhght Lamps — Miniature Tungsten Lamps — 
Flash Lights — The Electric Flat-iron — The Electric Toaster — 
Motors, Fuse Plugs — Electric Heaters — Intercommunicating Tele- 
phones — Electric Signals — Buzzers — Burglar Alarms — Annuncia- 
tors — Table Pushes — Bell-ringing Transformers — The Recording 
Wattmeter — To Read the Meter — State Regulation of Meter 
Service — Electric Batteries — Battery Formation — Battery Testers 
— Electric Conductors — Lamp Cord — Portable Cord — Annuncia- 
tor Wire — Private Electric Generating Plants — Storage Batteries 
—The Pilot Cell— National Electrical Code— Electric Light Wir- 
ing — Outlet Boxes — Automatic Door Switch — Plug Receptacles 
— Heater Switch, Pilot and Receptacle — Service Switch — ^Local 
Switches — Pilot Lights^ — Wall and Ceiling Sockets — Drop Lights. 

Index 385 



MECHANICS OF THE HOUSEHOLD 

CHAPTER I 

THE STEAM HEATING PLANT 

The use of steam as a means of heating dweUings is common 
in every part of the civihzed world. Plants of all sizes are con- 
structed, that not only give satisfactory service but are efficient 
in the use of fuel, and require the minimum amount of attention. 

The manufacture of steam heating apparatus has come to be 
a distinct industry, and represents a special branch of engineer- 
ing. Many manufacturing companies, pursue this line of busi- 
ness exclusively. The result has been the development of many 
distinctive features and systems of steam heating, that are very 
excellent for the purposes intended. 

Practice has shown that large plants can be operated more 
economically than small ones. Steam may be carried through 
underground, insulated pipes to great distances with but small 
loss of heat. This has lead to the sale of exhaust steam, from 
the engines of manufacturing plants, for heating purposes and 
the establishment of community heating plants, where the dwell- 
ings of a neighborhood are heated from a central heating plant; 
each subscriber paying for his heat according to the number of 
square feet of radiating surface his house contains. 

In the practice most commonly followed, with small steam 
heating plants, the steam is generated in a boiler located at any 
convenient place, but commonly in the basement. The steam 
is distributed through insulated pipes to the rooms, where it gives 
up its heat to cast-iron radiators, and from them it is imparted 
to the air; partly by radiation but most of the heat is trans- 
mitted to the air in direct contact with the radiator surface. 

The heating capacity of a radiator is determined by its out- 
side surface area, and is commonly termed, radiating surface or 
heating surface. Radiators of different styles and sizes are listed 
by manufacturers, according to the amount of heating surface 

1 



2 MECHANICS OF THE HOUSEHOLD 

each possesses. Radiators are sold at a definite amount per 
square foot, and may be made to contain any amount of heating 
surface, for different heights from 12 to 45 inches. 

The widespread use of steam as a means of heating buildings 
is due to its remarkable heat content. When water is converted 
into vapor the change is attended by the absorption of a large 
amount of heat. No matter at what temperature water is 
evaporated, a definite quantity of heat is required to merely 
change the water into vapor without changing its temperature. 
The heat used to vaporize water in a steam boiler is given up in 
the radiators when the steam is condensed. It is because of this 
property that steam is such a convenient vehicle for transferring 
heat from the furnace — where it is generated — to the place to 
be warmed. This heat of vaporization is really the property 
which gives to steam its usefulness as a means of heating. 

Heat of Vaporization. — The temperature of the steam is com- 
paratively an unimportant factor in the amount of heat given 
up by the radiator. It is the heat liberated at the time the steam 
changes from vapor to water that produces the greatest effect in 
changing the temperature of the house. This evolution of heat 
by condensation is sometimes called the latent heat of vaporiza- 
tion. It is the heat that was used up in changing the water to 
vapor. The following table of the properties of steam shows the 
temperatures and exact amounts of latent heat that correspond 
to various pressures. 

When water at the boiling point is turned into steam at the 
same temperature, there are required 965.7 B.t.u. for each pound 
of water changed into steam. In the table, this is the latent 
heat of the vapor of water at 0, gage pressure. As the pressure 
and corresponding temperature rise, the latent heat becomes 
less. At 10 pounds gage pressure, the temperature of the steam 
is practically 240°F., but the heat of vaporization is 946 thermal 
units. When the steam is changed back into water, as it is when 
condensed in the radiators, this latent heat becomes sensible and 
is that which heats the rooms. The steam enters the radiators 
and, coming into contact with the relatively colder walls, is con- 
densed. As condensation takes place, the latent heat of the 
steam becomes sensible heat and is absorbed by the radiators 
and then transferred to the air of the rooms. 



THE STEAM HEATING PLANT 
Properties of Steam 



Absolute pressure 


Gage pressure 


Temperature 


Latent heat 





14.7 


212.00 


965.70 


1 


15.0 


213.04 


964.96 


2 


16.0 


216.33 


962.63 


3 


17.0 


219.45 


960.49 


4 


18.0 


220.40 


958.32 


5 


19.0 


225.25 


958.30 


6 


20.0 


227.95 


954.38 


7 


21.0 


230.60 


952.50 


8 


22.0 


233.10 


950.62 


9 


23.0 


235.49 


949.03 


10 


24.0 


237.81 


947.37 


11 


25.0 


240.07 


945.76 


12 


26.0 


242.24 


944.25 


13 


27.0 


244.32 


942.74 


14 


28.0 


246.35 


941.29 


15 


29.0 


248.33 


939.88 


16 


30.0 


250.26 


938.50 


17 


31.0 


252.13 


937.17 


18 


32.0 


253.98 


935.45 


19 


33.0 


255.77 


934.57 


20 


34.0 


257.52 


933.32 . 


21 


35.0 


259.22 


932.10 


22 


36.0 


260.88 


930.92 


23 


37.0 


262.50 


929.76 


24 


38.0 


264.09 


928.62 


25 


39.0 


265.65 


927.51 



Whenever water is evaporated, heat is used up at a rate that 
in amount depends on its temperature and the quantity of water 
vaporized. This heat of vaporization is important, not only in 
problems which relate to steam heating but in all others where 
vapor of water exerts an influence — ventilation of buildings, 
atmospheric humidity, the formation of frost, refrigeration, and 
many other applications in practice; this factor is one of the 
important items in quantitative determinations of heat. It will 
appear repeatedly in considering ventilation and humidity. 

At temperatures below the boiling point of water, the heat of 
vaporization gradually increases until, at the freezing point,' 
it is 1092 B.t.u. Water vaporizes at all temperatures — even 
ice evaporates — and the cooling effect produced by evapora- 



4 MECHANICS OF THE HOUSEHOLD 

tion from sprinkled streets in summer, or the chilling sensation 
brought about by the winds of winter are caused largely because 
of its effect. The evaporation of perspiration from the body is 
one of the means of keeping it cool. At the temperature of the 
body 98.6 the heat of vaporization is 1046 B.t.u. 

Steam Temperatures. — While the temperature of steam is an 
unimportant factor in the heating of buildings there are many 
uses in which it is of the greatest consequence. When steam is 
employed for cooking or baking it is not the quantity of heat but 
its intensity that is necessary for the accomplishment of its 
purpose. 

Steam cookers must work at a temperature suitable to the 
articles under preparation, and the length of time required in the 
process. Examination of the table on page 3, will show that 
steam at the pressure of the air or 0, gage pressure, has a 
temperature of 212°r., which for boiling is sufficiently intense for 
ordinary cooking; but for all conditions required of steam cook- 
ing, a pressure of 25 pounds gage pressure is required. The tem- 
perature corresponding to 25 pounds is shown in the table as 
267°F. Baking temperatures for oven baking as for bread 
requires temperatures of 400°F. or higher. To bake by steam 
at that temperature would require a gage pressure of 185 pounds 
to the square inch. 

The British thermal unit is the English unit of measure of heat. 
It is the amount of heat required to raise the temperature of a 
pound of water 1°F. From the table it will be seen that 
steam at 10 pounds gage pressure, is only 27.4° hotter than 
it was at pounds. In raising the pressure of a pound of 
steam from to 10 pounds, the steam gained only 27.4 B.t.u. 
of heat. The amount of heat gained by raising the pressure to 
10 pounds is small as compared with the heat it received on vapor- 
izing. The extra fuel used up in raising the pressure is not well 
expended. It is customary, therefore, in heating plants, to use 
only enough pressure in the boiler to carry the steam through 
the system. This amount is rarely more than 10 pounds and 
oftener but 3 or 4 pounds pressure. 

Gage Pressure — Absolute Pressure. — In the practice of engi- 
neering among English speaking people, pressures are stated in 
pounds per square inch, above the atmosphere. This is termed 



THE STEAM HEATING PLANT 5 

gage pressure. It is that indicated by the gages of boilers, tanks, 
etc., subjected to internal pressure. Under ordinary conditions 
the term pressure is understood to mean gage pressure, the 
point being that of the pressure of the atmosphere. This system 
requires pressures below that of the atmosphere to be expressed 
as a partial vacuum, a complete vacuum being 14.7 pounds below 
the normal atmospheric pressure. 

In order to measure positively all pressures above a vacuum, 
the normal atmosphere is 14.7 pounds; all pressures above that 
point are continued on the same scale, thus: 

Gage pressure = 14.7 absolute 

Gage pressure 10 = 10 + 14.7 = 24.7 absolute 

Gage pressure 20 = 20 + 14 . 7 = 34 . 7 absolute 

Absolute pressures are, therefore, those of the gage plus the 
additional amount due to the atmosphere. All references to 
pressure in this work are intended to indicate gage pressure unless 
specifically mentioned as absolute pressure. 

Steam heating as applied to buildings may be considered under 
two general methods: the pressure system in which steam under 
pressure above the atmosphere is utilized to procure circulation; 
and the vacuum system in which the steam is used at a pressure 
below that of the atmosphere. Each of these systems is used 
under a great variety of conditions, and to some is applied spe- 
cific names but the principle of operation is very much the same 
in all of a single class. 

Steam heating plants are now seldom installed in the average 
home but they are very much employed in apartment houses and 
the larger residences. In large buildings and in groups of build- 
ings heated from a central point, steam is used for heating almost 
exclusively. The type of plant employed for any given condi- 
tion will depend on the architecture of the buildings and their 
surroundings. In very large buildings and in groups of buildings, 
the vacuum system is very generally employed. This system 
has, as a special field of heating, the elaborate plants required in 
large units. 

The low-pressure gravity system of heating is used in build- 
ings of moderate size, large residences, schools, churches, apart- 
ment houses, and the like. Under this form of steam heating is 





6 MECHANICS OF THE HOUSEHOLD 

to be included vapor heating systems. This is the same as the 
low-pressure plant except that it operates under pressure only 
slightly above the atmosphere and possesses features that fre- 
quently recommend its use over any other form of steam heating. 
The term vapor heating is used to distinguish it from the low- 
pressure system. 

The low-pressure gravity system, with which we are most 
concerned, takes its name from the conditions under which it 

works. The low pressure re- 
fers to the pressure of the 
steam in the boiler, which is 
generally 3 or 4 pounds; and 
since the water of condensation 
flows back to the boiler by 
reason of gravity, it is a gravity 
system. 

The placing of the pipes 
2ff ^ which are to carry the steam 

to the radiators and return the 
water of condensation to the 
boiler may consist of one or 
both of two standard arrange- 
ments. They are known as 
the single-pipe system and the 
twO'pipe system. 

Fig. 1 shows a diagram of a 
single-pipe system in its sim- 
-c, ' '^. ' I T ' plest form. In the figure the 

riG. 1. — Diagram of a gravity system ^ , ^ 

steam heating plant. pipe marked supply and return^ 

connects the boiler with the 
radiators. From the vertical pipe called a riser, the steam is 
taken to the radiators through branch pipes that all slope toward 
the riser, so that the water of condensation may readily flow back 
into the boiler. The water of condensation, returning to the 
boiler, must under this condition, flow in a direction contrary to 
the course of the steam supplying the radiators. In Fig. 2 is 
given a simple application of this system. A single pipe from 
the top of the boiler, in the basement, marked supply and re- 
turn pipe, connects with one radiator on the floor above. The 




THE STEAM HEATING PLANT 7 

radiator and all of the connecting pipes are set to drain the 
water of condensation into the boiler. 

When the valve is opened to admit steam to the radiator, the 
air vent must also be opened to allow the escape of the contained 
air. The steam will not diffuse with the air in the radiator and 
unless the air is allowed to escape, the steam will not enter. As 
the steam enters the cold radiator, it is rapidly condensed, and 
collects on the walls in the form of dew, at the same time giving 
up its latent heat. The heat is liberated as condensation takes 
place, and as the dew forms on the radiator walls the heat is 



Radiator 




FiQ. 2. — A simple form of steam heating plant. The furnace fire is controlled 
by a thermostat and a damper regulator. 

conducted directly to the iron. The water runs to the bottom 
of the radiator and then through the pipes, back to the boiler. 
The water occupies but relatively a little space and may return 
through the same pipe, while more steam is entering the radiator. 
As the steam condenses in the radiator, its reduction in volume 
tends to reduce the pressure and thus aids additional steam from 
the boiler to enter. In this manner a constant supply of heat 
enters the radiator in the form of steam which when condensed 
goes back to the boiler at a temperature very near the boiling 
point to be revaporized. It should be kept in mind that it is the 



8 



MECHANICS OF THE HOUSEHOLD 



heat of vaporization, not the temperature of the steam that is 
utiHzed in the radiator, and that the heat of vaporization is the 
vehicle of transfer. The water returning to the boiler may be at 
the boiling point and the steam supplying the heat to the radiators 
may be at the same temperature. 

Fig. 3 is a slightly different arrangement of the same boiler as 
that shown in Fig. 2, connected with two radiators on different 

Eadiator 



rif Air Yent 




Fig. 3.- 



-A gravity system steam heating plant of two radiators, 
is governed by a thermostat. 



The furnace 



floors. The same riser supplies both radiators with steam and 
takes the water of condensation back to the boiler. 

Fig. 4 is an example of the single-pipe system applied to a small 
house. In the drawing, the boiler in the basement is shown 
connected with four radiators on the first floor and three on the 
second floor. The pipes connecting with the more distant radia- 
tors are only extensions of the pipes connecting the radiators near 



THE STEAM HEATING PLANT 



9 



the boiler. As in Figs. 1, 2 and 3, all of the pipes and radiators 
are set to drain back into the boiler. If at any place the pipe is 
so graded that a part of the water is retained, poor circulation 
will result, because of the restricted area of the pipe, and the 
radiators will not be properly heated. This lack of drainage is 
also a common cause of hammering and pounding in steam sys- 
tems, known as water-hammer. The formation of water-hammer 
is caused by steam flowing through a water-restricted area, into 
a cold part of the system, where condensation takes place very 




Fig. 4. — The gravity system steam heating plant installed in a dwelling. 

rapidly. The condensation of the steam is so rapid and complete 
that the resulting vacuum draws the trapped water into the 
space with the force of a hammer stroke. The hammering will 
continue so long as the conditions exist. The pipes in the base- 
ment are suspended from the floor joists by hangers as shown in 
the drawing. In practice the pipes in the basement are covered 
with some form of insulating material to prevent loss of heat. 
As stated above, the single-pipe system may be successfully 
used in all house-heating plants except those of large size. It 



10 MECHANICS OF THE HOUSEHOLD 

requires the least amount of pipe and labor for installation of the 
circulating system and when well constructed performs very 
satisfactorily all of the functions required in a small heating plant. 

One of the commonest causes of trouble in a single-pipe system . 
is due to the radiator connections. The single radiator connec- 
tion requires the entering steam and escaping water of condensa- 
tion to pass through the same opening. Under ordinary condi- 
tions this double office of the radiator valve is accomplished with 
satisfaction but occasionally it is the cause of considerable noise. 
At any time the valve is left only partly open the steam will enter 
and condense because of the lower pressure inside the radiator 
but the condensed water will not be able to escape. The water 
has only the force of gravity to carry it out of the radiators and 
if it meets no opposition will flow back through the pipe to the 
boiler; but if it is required to pass a small opening through which 
steam is flowing in a contrary direction, the water will be retained 
in the radiators. Single-pipe radiators, therefore, work satis- 
factorily only under conditions which will permit the steam to 
enter and the water to leave as fast as it is formed. In ordinary 
use the valve at any time is apt to be left slightly open and this 
produces undesirable working conditions. 

In larger buildings, where greater distances require longer 
runs of pipe and more complicated connections, and where the 
volume of condensed steam is too great to be taken care of in a 
single pipe, this system does not work satisfactorily. 

Two-pipe System. — Fig. 5 is a diagram of a two-pipe system. 
Here, each radiator has a supply pipe, through which the steam 
enters, and a return pipe which conducts the water away. The 
branch pipes from a common supply pipe or riser, carry steam to 
the various radiators and all of the return pipes empty into a single 
return pipe that takes the water back to its source. It will be 
noticed that in this case the riser also connects at the bottom with 
the return pipe. This connection is made for the purpose of 
conducting away the condensation that takes place in the con- 
necting pipes. The water will always stand in these pipes, at 
the same height as the water in the boiler. The supply pipe from 
the boiler, and the branch pipes connecting the radiators all slope 
toward the riser. The condensation in the connecting pipes 
does not pass through the radiators as it returns to the boiler. 



THE STEAM HEATING PLANT 



11 



An exception to this general rule is shown in the radiator on 
the second floor. In this case the supply pipe slopes down- 
ward as it approaches the radiator. To prevent carrying water 
through the radiator, a small pipe under the left-hand valve con- 
nects with the return pipe and the water is thus conducted to the 
main return pipe. 

Fig. 6 is a simple application of the arrangement shown in 
Fig. 5. The steam may be easily traced from the boiler to the 
radiators, and back through 
the return pipes to its source. 
The pipe marked R is the 
connection between the main 
supply pipe and the return 
pipe that takes away the con- 
densation of the riser. It is 
connected to the main return 
pipe below the water line of 
the boiler and, therefore, does 
not interfere in any way with 
the passage of the steam. 
Each radiator empties its 
water of condensation into a 
common return pipe, that 
finally connects with the boiler 
below the water line. 

This arrangement may be 
elaborated to almost any ex- 
tent and is an improvement 
over the single-pipe system. 
It is quite commonly used as 
a method of steam distribu- 
tion, but it lacks the required 

elements necessary to a positive circulation. As an example: 
Suppose that the plant shown in Fig. 6 is working and that 
the radiator on the first floor is hot, but the valves of the 
radiator on the second floor are closed and it is cold. The steam 
entering at the valve A of the lower radiator is being condensed 
as fast as the heat is radiated. The steam will pass on through 
the valve B into the return pipe and as soon as the return pipe 




Fig. 5. — Diagram showing the arrange- 
ment of a two-pipe steam plant. 



12 



MECHANICS OF THE HOUSEHOLD 



becomes hot it will contain steam at practically the same pressure 
as that in the supply pipe. This is what takes place in every 
working steam plant. Now suppose that it is desired to heat 
the radiator on the floor above. The steam valve A of the upper 
radiator is opened to admit steam and the return valve is also 
opened to allow the water to escape. There is steam in both the 



Radiator 




Fig. 6. — A two-pipe steam heating plant. 

supply and return pipes of the radiator below at the same pres- 
sure, each tending to send steam into the radiator above at oppo- 
site ends. This would make a condition exactly the same ag a 
single-pipe system, with a supply pipe at both ends of the radiator 
and the result would, of course, be the same as in the single-pipe 
system. There being no place for the water to escape except 
against the incoming steam, the water will sometimes surge back 
and forth with the customary noises peculiar to such conditions. 
It must not be understood that this will always occur, because 



THE STEAM HEATING PLANT 



13 



systems of this kind are in use with fairly good results, but noisy 
radiators are not at all rare when working under this condition 
and the cause is from that described. To overcome this difficulty 
and change the system into one in which there would be a posi- 
tive circulation from A to B, in each radiator, allowing the steam 
always to enter at the valve A and escape at B, the system must 
be changed to that of separate returns. 

Separate -return System. — A diagram of a separate-return sys- 
tem is shown in Fig. 7. In this figure, the radiator, boiler and 
supply pipes are the same as 
those of Fig. 5, but there is a 
separate return pipe from 
each of the radiators, connect- 
ing with the main return pipe 
at a point below the water 
line of the boiler. Examina- 
tion of this diagram will show 
that there is an independent 
circuit for the steam through 
each radiator. The steam is 
taken frbm a common riser as 
before but after passing 
through the radiator the 
water is returned by a sepa- 
rate pipe to the main return _ 
pipe at the bottom of the 
boiler. Fig. 8 is an applica- 
tion of separate-return system. 
It is exactly the same as Fig. 
6, except that each radiator 
has an independent return 
pipe. Steam must always 
enter the radiators at the 

valves A and leave at the valves B, This makes a positive cir- 
culation that renders each radiator independent of the others. 
There is no opportunity for steam to pass through one radiator 
and interfere with the return water of another; it, therefore, pre- 
vents the possibility of hammering or surging so common in 
poorly designed steam systems. 




Fig. 7.- 



-Diagram of a separate return 
steam system. 



14 



MECHANICS OF THE HOUSEHOLD 



Of all the methods of steam heating where the water of con- 
densation is returned to the boiler by reason of gravity this is 
the most satisfactory. This plant requires a larger amount of 
pipe than the other systems described and as a consequence the 
cost of installation is greater but it repays in excellence of 
service the extra expense incurred. 



Badiator 



Thermostat 

I 





Fig. 8. — A separate return heating plant. 

Overhead or Drop System. — There is yet another gravity 
system of steam heating that is sometimes used in large buildings 
where economy in the use of pipe is desired; this is the overhead 
or drop system shown in Fig. 9. It is not a common method of 
piping and is given here only because of its occasional use. In 
the arrangement of the drop system, the supply pipe for the 
radiators rises from the boiler to the highest point of the system 
and the branch pipes for the radiators are taken off from the 
descending pipe. Its action is the same as that of a single-pipe 



THE STEAM HEATING PLANT 



15 



system but the advantage gained by the arrangement is that the 
steam in the main supply pipes travels in the same direction as 
the returning water of condensation; the cause of surging in long 
risers is thus eliminated. 

The two-pipe systems of steam heating are more certain in 
action than the single-pipe methods because there is nothing to 
interfere with the progress of 
the steam on its way to the 
radiators. In long branch 
pipes of the single-pipe sys- 
tem, the returning water is 
frequently caught by the ad- 
vancing steam and carried to 
the end of the pipe, when 
slugging and surging is the 
result. 

Water-filled Radiators. — 
Radiators frequently fill with 
water and are noisy because 
of the position of the valve. 
This may be true in any grav- 
ity system but particularly so 
in radiators having a single 
pipe. When the valve of a 
single-pipe radiator is opened 
a very small amount, the 
entering steam is immedia- 
tely condensed but the water 
cannot escape because the in- 
coming steam entirely fills the opening. Under this condition, the 
radiator may entirely fill with water. If the valve is then opened 
wide, the imprisoned water has an opportunity to escape while 
the steam is entering, but the entering steam and escaping water 
sets up a water-hammer that sometimes is terrific and lasts 
until the water is discharged from the radiator. The same 
condition may exist in a two-pipe system, if the steam valve is 
slightly opened while the escape valve is closed, but in a well- 
designed system the radiator will be immediately emptied when 
both valves are open. 




Fig. 9. — Diagram of the overhead or 
drop system steam plant. 



16 



MECHANICS OF THE HOUSEHOLD 



Air Vents. — All radiators must be provided with air vents. 
The vent is placed near the top of the last loop of the radiator, 
at the end opposite from the entering steam, as indicated in Figs. 
2, 3, 6, etc. The object of the vent is to allow the air to 
escape from the radiator as the steam enters. Steam will not 
diffuse with the air and, therefore, cannot enter the radiator 
until the air is discharged. The air vent may be a simple cock 
such as is shown in Fig. 10, that must be opened by hand when 
the steam is turned on, to allow the air to escape, and closed 
when the steam appears at the vent; or it may be an automatic 
vent, that opens when the radiator cools and closes automatically 
when the radiator is filled with steam. There are many makes 





A YI 


- 


(^ 


I^^Ljr 


^ ^ 






w^vwwv^ . 


'—I r ' _ 



c 

Fig. 10. Fig. 11. 

Fig. 10. — A common form of air vent for radiators. 
Fig. 11. — An inexpensive automatic radiator air vent. 
Fig. 12.— Monash No. 16 automatic air vent. 
Fig. 13. — The Allen float, radiator air vent. 



Fig. 12. 



of air vents of both hand-regulating and automatic types; of 
the former. Fig. 10 furnishes a common example. The part 
A J in the figure, is threaded and screws tightly into a hole made 
to receive it in the end loop of the radiator. The part B is s, 
screw-plug that closes the passage C, leading to the inside of the 
radiator. When the steam is turned on, the vent must be 
opened until the air is discharged, after which it is closed by the 
hand- wheel D, 

Automatic Air Vents, — These vents depend for their action on 
the expansion of a part of the valve due to the temperature of the 
steam. The valve remains closed when hot and opens when 
cold. The difference in temperature between the steam and the 
expelled air from the radiator is the controlling factor. In the 



THE STEAM HEATING PLANT 17 

automatic vent shown in Fig. 11, the part A is screwed into the 
radiator loop. The discharge C is open to the air or connected 
with a drip pipe, which returns the water to the basement. The 
cyHnder D, which closes the passage 5, is made of a material of a 
high coefficient of expansion. The piece D, when cool, is con- 
tracted sufficiently to leave the passage B open to the air. When 
the steam is turned on, the expelled air from the radiator escapes 
through B and (7, but when the steam reaches D the heat quickly 
expands the piece and closes the vent. 

Most automatic vents require adjusting when put in place and 
occasionally need readjustment. The cap 0, of Fig. 11, may be 
removed with a wrench and a screw-driver used to adjust the 
piece D, so as to shut off the steam when the radiator is filled 
with steam. The expanding piece is simply screwed down until 
the steam ceases to escape. 

Fig. 12 is another style of automatic vent, constructed on the 
same principle as that of Fig. 11, but probably more positive in 
action. In this vent the part A attaches to the radiator. The 
expanding portion B is made in the form of a hollow cylinder, 
through which the air and steam escape to the atmosphere. It 
is longer than the corresponding piece in the other vent and is 
more sensitive because of its greater length and exposed surface. 
As the piece B elongates from expansion, the upper end makes a 
joint with the conical piece D. The shape of this latter piece 
gives better opportunity for a tight joint than in the other form 
of vent and in practice gives better service. 

Fig. 13 is a cross-section of the Allen vent. This is an example 
of a vent which depends for its action on a float. Whenever 
sufficient water accumulates in the body of the vent to raise 
the float, it closes the vent by means of its buoyancy. The body 
of the vent shown in Fig. 13 is composed of two concentric cylin- 
ders. The float E occupies the inner cylinder, while surrounding 
it is the outer cylinder D. The outer cylinder is entirely closed 
except a little hole at G. The float is made of light metal and 
fits loosely in the inner cylinder. The steam from the radiator 
condenses in the vent until the inner cylinder is filled with water, 
up to the opening A, The float by its buoyancy keeps the open- 
ing in B stopped, and no steam can escape. The air of the outer 
cylinder D is expanded by the heat of the steam and most of the 



18 



MECHANICS OF THE HOUSEHOLD 



air escapes through the hole G. When the radiator cools, the 
rarefied air in D contracts and draws the water from the inner 
cylinder into the space D; this allows the float to fall and unstop 
the opening in B. When the steam again reaches the vent, the 
heat expands the air in D and forces the water into the inner 
cylinder; the float is again raised and stops the opening in B. 

Many other air vents are in common use but most of them 
operate on one or the other of the principles described. Fig. 11 
is a relatively inexpensive vent, while Fig. 12 is higher-priced. 

Steam Radiator Valves. — ^Like most other mechanical appli- 
ances that are extensively used, radiator valves are made by a 
great number of manufacturers and in many different forms. 





Fig. 14. — Steam radiator 
valve. 



Fig. 15. — Sectional view of a 
steam radiator valve. 



Some possess special features that are intended to increase their 
working efficiency but the type of radiator valve most commonly 
used for ordinary construction is that illustrated in Figs. 14 and 
15. It is a style of angle valve that takes the place of an elbow 
and being made with a union joint, also furnishes a means of 
disconnecting the radiator without disturbing the pipes. Fig. 
14 is an outside view of the valve and Fig. 15 shows its mechan- 
ical construction. The part B screws onto the end of the steam 
pipe and A connects with the radiator. The part C-D is the 
union. The nut C screws onto the valve and makes a steam- 



THE STEAM HEATING PLANT 19 

tight joint at D, between the parts. In case it is desired to 
remove the radiator, it furnishes an easy means of detaching the 
valve. The composition valve-disc E makes a seat on the brass 
ring directly under it, to shut off the steam. In case the valve 
leaks, the disc may be removed by taking the valve casing apart 
at G. The worn disc can then be replaced with a new one which 
may be obtained from the dealer who furnishied the valve. The 
only moving part of the valve exposed to the air. is at the point 
where the valve-stem S enters the casing. The joint is made 
steam-tight by the packing P. The packing is greased candle 
wicking that is wound around the stem and held tightly in place 
by the screw-cap H, If the valve leaks at this joint, a turn or 
two with a wrench will stop the escape of the steam. 

THE HOUSE-HEATING STEAM BOILER 

House-heating boilers were formerly made of sheet metal and 
are still so constructed to some extent, but by far the greater 
number are now made of cast iron. Sheet-metal boilers are 
constructed at the factory, ready to be installed, but the cast-iron 
type is made in sections and assembled to make a complete 
boiler, at the time the plant is erected. Sectional boilers are 
convenient to install, on account of the possibility of handling 
the parts in a limited space, that would not admit an assembled 
boiler without tearing down a part of the basement for admission. 

Cast-iron boilers as commonly used for heating dwellings are 
made in two definite styles. The small sizes are cylindrical in 
form and are used for either steam or hot-water heating. The 
larger sizes are made as illustrated in Figs. 16 and 17, the 
former being an outside view, and the latter showing the internal 
arrangement of the same boiler. The fire-box, water space and 
smoke passages are easily recognized. Each division represents 
a separate section which assembled as that in the figures makes a 
complete boiler with a common opening as shown at the top of 
Fig. 17. These boilers are used for residences of large size and 
for buildings of less than 10,000 feet of radiating surface. For 
large buildings, the steam is most commonly generated in boilers 
built for high pressure. 

In small plants, intended for either steam or hot-water heating, 



20 



MECHANICS OF THE HOUSEHOLD 



the cylindrical style of boiler shown in Fig. 18 is commonly used. 
As constructed by different manufacturers, the parts differ quite 
materially but Fig. 18 shows all of the essential features and 
serves to illustrate the different working parts. The sejctions 
into which the boiler is divided are indicated on the left-hand 
side of the figure by the numbers 1 to 6. The parts from 1 to 5 
are screwed together with threaded nipples, joining the central 
column. The part 6 contains the grate and the ash-pit, with 
the draft and clean-out doors. 




Fig. 16. Fig. 17. 

Fig. 16. — Sectional cast-iron boiler for steam or hot-water heating. 
Fig. 17 — Interior view of the boiler shown in Fig. 16. 



The drawing shows the boiler cut through the middle length- 
wise and exposes to view all of the essential features. The fire- 
box and the spaces occupied by the steam and water are easily 
recognized. It will be seen that the water space surrounds the 
fire-box except at the bottom and that the space above the fire- 
box presents a large amount of heating surface to the flame and 
heated gases as they pass to the chimney. The arrows show 
their course; first through the openings near the center, then 
through those further away. The object being to keep the 



THE STEAM HEATING PLANT 



21 



heat as long as possible in contact with the heating surfaces 
without interfering with the draft. 

There is no standard method of rating the heating capacity of 
boilers of this kind and as a consequence, boilers of different 
makes — for the same rating-^are not the same in actual heating 
capacity. The boilers are sold by their makers in sizes that 




Fig. 18. — Sectional view of the cylindrical type of cast-iron, sectional boiler. 

are intended to furnish heat sufficient to supply a definite num- 
ber of square feet of radiating surface. The ratings are quite 
generally too high for the weather conditions of the Northwest. 
A common practice with contractors is to select boilers for a 
given plant 50 per cent, and even 100 per cent, larger than those 
rated by the manufacturers for the same amount of radiation. 



22 



MECHANICS OF THE HOUSEHOLD 



Some manufacturers sell their boilers at honest ratings but they 
are exceptions. 

In specifying the capacity of a house-heating plant it is common 
practice to require the boiler to be of such size as will easily 
heat a definite number of square feet of radiating surface. The 
radiators are required to possess sufficient radiating surface to 
keep the house at 70°r. in any weather. In the absence of any 
rules or specifications for determining the heating capacity of the 
boiler, the only means of securing a satisfactory plant is to require 
a guarantee of the contractor to install a 
boiler such as will fulfil the conditions stated 
above. 

Boiler Trimmings. — Attached to the 
boiler and required for its safe operation are 
a number of appliances that demand special 
attention. The office of each part should be 
thoroughly appreciated and the mechanical 
construction should be fully understood. 
An intimate acquaintance with the details of 
the plant, helps to make its operation satis- 
factory and adds to the efficiency with which 
it can be made to perform its duty. 

The Water Column.— In Fig. 18 the 
water column is shown at C It is attached 
to the boiler by pipes at points above and 
below the water line, so as to allow a free 
passage of the water of the boiler to the in- 
The water line should be 3 or 4 inches above the top 
Attached to the water column is the gage-glasSj 




Fig. 



19.~The water 
gage. 



tenor, 

heating surface 

the try-cocks T and T and the steam gage G. 

The object of the gage-glass is to show the height of the water 
in the boiler. It is shown in place on the boiler in Figs. 16 and 
18 and in detail in Fig. 19. The lower part of the gage-glass 
occupies a position on the boiler about 2 inches above the top 
heating surface. When the boiler is working, the level of the 
water should always be visible in the glass and should stand 
normally one-third to one-half full. 

The water gage is attached to the water column by two brass 
valves V, The valves are provided so that in case the water 



THE STEAM HEATING PLANT 23 

glass should be broken the openings may be closed. The ends 
of the glass are made tight by ^'stuffing-boxes^' marked C, in the 
figure. The packing S is generally in the form of rubber rings 
but greased wicking may be used if necessary as in the case of 
valve-stems. 

The try-cocks T and T (Fig. 18) are also intended to indicate the 
approximate height of the water in the boiler and should the water 
glass be broken may be used in its place. The openings of the try- 
cocks point toward the floor. When a cock is opened, should 
steam alone escape, it will be absorbed by the air, but if water is 
escaping, although much of it will be vaporized and look like 
steam, some of the water will be carried to the floor and produce 
a wet spot. When the cock is opened wide the escaping water 
from the lower cock should always wet the floor. 

The drip-cock P (Fig. 18) at the bottom of the gage-glass is 
for draining the water column and for blowing out any deposit 
that may collect in the opening of the column. This cock should 
be opened occasionally to assure the correctness of the gage-glass. 

The Steam Gage. — Steam pressure is measured in pounds to 
the square inch above the pressure of the atmosphere. The 
gages used for indicating the pressure of 
the steam are made in several forms but 
the type most commonly used is that 
shown in Fig. 20. It is known as the 
Bourdon type of gage and takes its name 
from the bent tube A, which furnishes its 
active principle. The Bourdon barometer 
invented in 1849 employed this form of 
sensitive tube. In the drawing the face ^ 

of the gage has been removed to show Fig. 20.— Typical Bour- 
the working parts. The sensitive part is f""'^ pressure gage with the 

® ^ . face removed. 

the flat elastic tube A, which is bent in 

the form of a circle. When the pressure of the steam enters at 
S the air in the tube is compressed and the tube tends to straighten. 
The movement of the tube caused by the steam pressure is com- 
municated to the pointer by a link connection and gear as shown 
in the drawing. The amount of straightening of the tube will 
be in proportion to the steam pressure and is indicated by the 
numbers marked on the face of the gage. When the pressure is 




24 



MECHANICS OF THE HOUSEHOLD 



released, the tube returns to its original position and the spiral 
spring C turns the hand back to its first position. 

The Safety Valve. — All steam boilers should be provided 
with safety valves as a safeguard against excessive steam pres- 
sures. Of the various types of safety valves, that known as the 
pop-valve is most commonly used on house-heating boilers. It 
is indicated at W in Fig. 18 and is shown in section in Fig. 21. 
The part A is screwed into the top of the boiler at any convenient 
place. The pressure of the spring C holds the valve B on its seat 
until the internal pressure reaches a certain in- 
tensity at which the valve is set, when it opens 
and allows the excess steam to escape. When 
the pressure is reduced, the spring forces the 
valve back on its seat. The handle D permits 
the valve to be lifted at any time as an assur- 
ance that it is in working order. This should 
be done occasionally, as the valve may stick to 
the seat after long standing and allow the pres- 
sure to rise above the point at which it should 
^^pop.'^ 

The valve may be set to ^^blow off ^' at any de- 
sired pressure by the adjusting piece E: House- 
heating boilers generally have their safety valves 
set to blow off at 8 or 10 pounds. 

The Draft Regulator. — As a means of auto- 
matic control of the steam pressure, the draft regulator is fre- 
quently used to so govern the fire that when a certain steam 
pressure is reached, the direct draft will be automatically closed 
and the check-draft damper opened. The draft regulator is 
shown in place at D in Fig. 18, and will also be found in Fig. 16. 
A detailed description of the regulator will be found on pages 
60 and 61. 

RULE FOR PROPORTIONING RADIATORS 




Fig. 21. — Cross- 
section of a pop 
valve. 



Rules for determining the amount of radiating surface that 
will be required to satisfactorily heat a building to 70°F. regard- 
less of weather conditions are entirely empirical, that is, they are 
derived from experience. It is evident that no definite rule can 



THE STEAM HEATING PLANT 25 

be established that will take into account the method of building 
construction, the kind and amount of materials that make up 
the walls and the quality of workmanship employed. These 
variable quantities coupled with the changing climatic conditions 
of temperature and wind velocity produce a complication that 
cannot be overcome in a formula that will give exact results. 

Many rules are in use for this purpose, no two of which give 
exactly the same results when applied to a problem. A common 
practice is to apply one of the rules in use and then under 
conditions of exceptional exposure, to add to the amount thus 
calculated as experience may dictate. 

The following rule by Professor R. G. Carpenter of Cornell 
University was taken from a handbook published by the J. L. 
Mott Iron Works of New York. This company manufactures 
and deals in all kinds of apparatus entering into steam and hot- 
water heating and the rule is given as one that has produced 
satisfactory results. 

Rule. — Add the area of the glass surface in the room to one-quarter 
of the exposed wall surface, and to this add from one-fifty-fifth to 
three-fifty-fifths of the cubical contents (one-fifty-fifth for rooms on 
upper floor, two-fifty-fifths for rooms on first floor and three-fifty-fifths 
for large halls); then for steam multiply by 0.25, and for hot water 
by 0.40. 

Example. — A room 20 by 12 by 10 feet with glass exposure of 48 
feet, }^i of wall exposure (two sides exposed) 320 feet = 80, J^5 of 
2400 = 44. 

48 + 80 -f 44 = 172 X 0.25 = 43 feet. 
If you add %5 the surface would be 54 feet. 
If you add %5 the surface would be 65 feet. 

PROPORTIONING THE SIZE OF MAINS 

For any size system of steam or water heating the following 
rule will be found entirely satisfactory for mains 100 feet long; 
for each 100 feet additional use a size larger ratio. 

Rule. — • 

a r 

r represents ratio of main in inches for each 100 feet of surface; </, 
diameter of pipe; R, quantity of radiation carried by size of pipe; a, 
area of pipe in inches. 



26 MECHANICS OF THE HOUSEHOLD 

From this the following table has been constructed: 









Quantity of radia- 


'Diameter of pipe 


Area of pipe 


Ratio to each 100 
feet of surface 


tion, steam or 

water, on a 

given size pipe 


IK 


1.767 


2.10 


84 


2 


3.141 


1.57 


200 


2M 


4.908 


1.25 


400 


3 


7.069 


1.04 


700 


3M 


9.621 


0.90 


1,062 


4 


12.566 


0.78 


1,590 


4K 


15.904 


0.70 


2,272 


5 


19.625 


0.63 


3,120 


6 


28.274 


0.52 


5,440 


7 


38.484 


0.45 


8,550 


8 


50.265 


0.40 


12,556 


9 


63.617 


0.35 


18,100 


10 


78.540 


0.30 


25,300 



FORMS OF RADIATORS 

Radiators are much the same in appearance for both steam and 
hot- water heating. They are hollow cast-iron columns so de- 
signed that they may be fastened together in units of any number 
of sections. The sections are made in size to present a definite 
number of square feet of outside surface that is spoken of as 
radiating surface. The amount of radiating surface in any 
radiator depends on its height and the contour of the cross-sec- 
tion. The radiator sections may be made in the form of a single 
column as Fig. 22 or they may be divided into two, three, four or 
more columns to increase their radiating surface. 

The following table, taken from a manufacturer's catalogue, 
shows the method of rating the heating capacity of a particular 
design. In the table, the first column gives the number of sec- 
tions in the radiator, the second column states the length of the 
radiator in inches. The columns headed heating surface give 
the heights of the sections in inches and the amount of radiating 
surface in various radiators of different heights and numbers of 
sections. As an example: This table refers to the three-column 
radiators of Fig. 23. Such a radiator 32 inches high with 10 



THE STEAM HEATING PLANT 



27 



sections would contain 45 square feet of radiating surface and 
would be 25 inches in length. 





U4 

■S ° 


Heating surface — square feet 


s 

o 
'•+3 
o 

O) 
«a 

6 


CO 

d ^ 

•C CO 


1 

6 

A 

W) . 

.at 

CO 


d "" 


COCO 


d=" 




2 


5 


12 


10 


9 


7% 


6% 


5% 


3 


7M 


18 


15 


13M 


11% 


9% 


8% 


4 


10 


24 


20 


18 


15 


13 


11 ' 


5 


12>^ 


30 


25 


22K 


18% 


16% 


13% 


6 


15 


36 


30 


27 


22% 


19% 


16% 


7 


i7y2 


42 


35 


31K 


26% 


22% 


19% 


8 


20 


48 


40 


36 


30 


26 


22 


9 


22K 


54 


45 


mi 


33% 


29% 


24% 


10 


25 


60 


50 


45 


37% 


32% 


27% 


11 


27M 


66 


55 


49K 


41% 


35% 


30% 


12 


30 


72 


60 


54 


45 


39 


33 


13 


32M 


78 


65 


58K 


48% 


42% 


35% 


14 


35 


84 


70 


63 


52% 


45% 


38% 


15 


37>i 


90 


75 


67>^ 


56% 


48% 


41% 


16 


40 


96 


80 


72 


60 


52 


44 1 


17 


42H 


102 


85 


76K 


63% 


55% 


46% 


18 


45 


108 


90 


81 


67% 


58% 


49% 


19 


47% 


114 


95 


85M 


71% 


61% 


52% 


20 


50 


120 


100 


90 


75 


65 


55 


21 


52Ji 


126 


. 105 


941^ 


78% 


68% 


57% 


22 


55 


132 


110 


99 


82% 


71% 


60% 


23 


57H 


138 


115 


103K 


86% 


74% 


63% 


24 


60 


144 


120 


108 


90 


78 


66 


25 


62>^ 


150 


125 


112M 


93% 


81% 


68% 


26 


65 


156 


130 


117 


97% 


84% 


71% 


27 


67% 


162 


135 


121M 


101% 


87% 


74% 


28 


70 


168 


140 


126 


105 


91 


77 


29 


72% 


174 


145 


130K 


108% 


94% 


79% 


30 


75 


180 


150 


135 


112% 


97% 


82% 


31 


77% 


186 


155 


139K 


116% 


100% 


85% 


32 


80 


192 


160 


140 


120 


104 


88 



Fig. 22 is a radiator made up of eight single-column sections. 



28 



MECHANICS OF THE HOUSEHOLD 



In Fig. 23 is shown five three-column radiators, varying in 
height from 20 to 45 inches. 

The sections of steam radiators are joined together at the bot- 
tom with close-nippleSj so as to leave an opening from end to 
end. The sections of hot-water radiators are joined in the same 
manner, except that there is an opening at both top and bottom. 
Fig. 30 shows the openings of a hot-water radiator installed as 
direct-indirect heater. Fig. 24 illustrates a special form of 
radiator that is intended to be placed under windows and in 

other places that will not admit the high 
form. Such a radiator as that shown 
in the picture is often covered with a 
window seat and in cold weather becomes 
the favorite place of the sitting room. 
Another special form is that of Fig. 25. 





Fig. 22. Fig. 23. 

Fig. 22. — Single column steam radiator. 

Fig. 23. — Three-column radiators of different heights; for steam or hot-water 
heating. 



As a corner radiator this style is much to be preferred to the 
ordinary method of connection; here the angle is completely 
filled — there is no open space in the corner. 

Wall radiators such as shown in Fig. 26 are made to set 
close to the wall, where floor space is limited. They are par- 
ticularly adapted for use in narrow halls, bathrooms and other 
places where the ordinary type could not be conveniently used. 

A radiator that will appeal to all neat housekeepers is that of 
Fig. 27. It does not stand on the floor as in the case of the 



THE STEAM HEATING PLANT 



29 



ordinary type, but is hung from the wall by concealed brackets. 
The difficulty of sweeping under this radiator is entirely avoided. 
Fig. 28 is a radiator designed to furnish a warming oven for 
plates and for heating the room at the same time. It is some- 
times installed in dining rooms. 




Fig. 24.- 



-Six-column, low form of hot-water radiators to be placed under 
windows. 



The ordinary method of heating by the use of radiators is 
known as the direct method. The air is heated by coming 
directly into contact with the radiators and distributed through 





Fig. 25. — Two-column corner 
radiator for steam heating. 



Fig. 26. — Wall form, radiator for stonm 
or hot water. 



the room by convection. If the arrangement is such that the 
air is brought from outdoors and heated by the radiator before 
entering the room, it is called the indirect method of heating.- 
Such an arrangement is illustrated in Fig. 29. The radiator 



30 



MECHANICS OF THE HOUSEHOLD 



is located beneath the floor, in a passage that takes the air from 
outdoors and after being heated, enters the room through a 
register located in the wall. 

Fig. 30 is still another arrangement known as the direct-indirect 
method of heating. The radiator is placed in position, as for 
direct heating, but the air supply is taken from outdoors. The 
radiator base is enclosed and a double damper T regulates the 
amount of air that comes from the outside. When the inside 
damper is closed and the outside damper is open, as is shown in 
the drawing, the air comes from outdoors and is heated as it 
passes through the radiator on its way to the room. If the 
dampers are reversed, the air circulates through the radiator as 
in the case of direct radiation. 





Fig. 27. — Two-column radiator 
suspended from the wall by 
brackets. 



Fig. 28. — D i n i n g-room 
radiator containing a warm- 
ing oven. 



In the use of the direct or the direct-indirect method of heating 
the principal object to be attained is that of ventilation, but 
quite generally the passages are so arranged that the air may be 
taken from outdoors or, if desired, the air of the house may be 
sent through the radiators to be reheated. In extremely cold 
and windy weather it is sometimes difficult to keep the house at 
the desired temperature when all of the air supply comes from 
the outside. Under such conditions the outside air is used only 
occasionally. In mild weather it is common to use the outdoor 
air most of the time. The cost of heating, when these methods 
are used, is higher than by direct radiation, because the air is 



THE STEAM HEATING PLANT 



31 



being constantly changed in temperature from that of the out- 
side to 70°. 

Radiator Finishings. — In steam and hot-water heating the 
decoration of the radiators is a much more important item than 
that of a good-looking surface or one which will harmonize with 
the setting. Until recently radiator finishing has been con- 
sidered a minor detail and the familiar bronze has been looked 




Fig. 29. — Ventilation by the indirect 
method of heating. 



Fig. 30. — Ventilation by the direct- 
indirect method of heating. 



upon as a standard covering, while painted radiators were con- 
sidered only a matter of taste. The character of the surface is, 
however, the determining factor in the quantity of heat given 
out by radiators. This has been determined in the experimental 
laboratory of the University of Michigan by Professor John A. 
Allen. Comparison was made of bare cast-iron radiators with 
the same forms painted as indicated in the following table. The 
bare radiator was taken at 100 per cent.; the other finishes 



32 MECHANICS OF THE HOUSEHOLD 

are expressed in per cent, above or below that of the bare 
radiator. 

Condensing 
capacity, 
per cent. 

No. 1, a cast-iron radiator, bare as received from the foundry 100 
No. 2, a cast-iron radiator, coated with aluminum bronze. ... 78 
No. 3, a cast-iron radiator, three coats of white enamel paint . . 102 

No. 4, a cast-iron radiator, coated with copper bronze 80 

No. 5, a cast-iron radiator, three coats of green enamel paint. 101 
No. 6, a cast-iron radiator, three coats of black enamel paint. 101 

The author has stated further that, ''It might be said in gen- 
eral that all bronzes reduce the heating effect of the radiator 
about 25 per cent, while lead paints and enamels give off the same 
amount of heat as bare iron. The number of coats of paint on 
the radiator makes no difference. The last coat is always the 
determining factor in heat transmission.'' 

PIPE COVERINGS 

All hot-water or steam pipes in the basement and in other 
places not intended to be used for heating should be covered 
with some form of insulating material. At ordinary working 
temperature a square foot of hot pipe surface will radiate about 
15 B.t.u. of heat per minute. To prevent this loss of heat and 
the consequent waste of fuel the pipes should be covered with 
some form of insulating material. 

Pipe coverings are made of many kinds of material and some 
possess insulating properties that may reduce the loss to as low 
a point as 15 per cent, of the amount radiated by a bare pipe. 
Many good insulating materials do not give satisfactory results 
as pipe coverings because they do not keep their shape, some 
cannot be considered in the average plant because of high cost. 

Wood-pulp paper is extensively used as a cheap covering; 
it is a good insulator and under ordinary conditions makes a 
satisfactory covering. A more efficient and also a more expensive 
covering th^t is extensively used is that made of magnesia 
carbonate and known as magnesia covering. Aside from these, 
other forms made of cork, hair-felt, asbestos and composition 
coverings are sometimes used in house-heating plants. 

In selecting a pipe covering, there should be taken into account 



THE STEAM HEATING PLANT 33 

not only its insulating properties but its ability to resist fire, 
dampness or breeding places for vermin. It rests entirely with 
the owner whether he covers the pipes with a combustible or an 
incombustible material when the insulating properties are about 
the same. Coverings made of animal or vegetable materials 
under some conditions furnish a breeding place for vermin. 

Pipe coverings are made in sections about 3 feet in length and 
from 1 to 1% inches in thickness. The sections are usually 
cut in halves lengthwise to permit being put in place. The 
sections are covered with common muslin to keep the material 
in place and sometimes are painted after being installed. Paint- 
ing has nothing to do with their insulating capabilities, but it 
preserves the cloth and makes a neat appearance. The sections 
when put in place are secured by pasting one of the loose edges 
of the cloth to the surface. The ends of the sections are bound 



Fig. 31. — Pipe covering. 

together with strips of metal. Fig. 31 shows the appearance of 
the pipe when the covering is in place. 

Irregular surfaces like the body of the furnace, pipe connec- 
tions, etc., are insulated by coverings made from a plaster that 
is made expressly for such work. It is known as asbestus plaster. 
The plaster may be purchased in bulk and put in place with a 
trowel. As it is found in the market the plaster requires only 
the addition of water to put into working form. 

The value of a pipe covering is not in proportion to its thick- 
ness. Experiments with pipe coverings have shown that a thick- 
ness of 1% inches will reduce the radiation 90 per cent., but 
doubling the thickness reduces the loss only 5 per cent. It, 
therefore, does not pay to make a covering more than IJ^s inches 
thick. 

Vapor-system Heating. — This system of heating is not greatly' 
different from the steam plants already described but it is 
operated under conditions which do not permit the steam in the 



34 MECHANICS OF THE HOUSEHOLD 

boiler to rise beyond a few ounces of pressure. Since the plant 
is intended to work at a pressure that is scarcely indicated by 
an ordinary steam gage, it has been termed a vapor system to 
distinguish it from the pressure systems which employ steam, up 
to 5 pounds or more to the square inch. The heat is trans- 
mitted to the radiators in the same manner as in the pressure 
systems. The heat of vaporization of steam is somewhat greater 
at the boiling point of water than at higher pressures, and the 
lack of pressure, therefore, increases its heating capacity. . This 
is shown in the table, properties of steam, on page 3. The 
successful operation of such a plant rests in the delivery of the 
vapor to the radiators at only the slightest pressure and the 
return of the condensate to the boiler without noise or obstruction 
to the circulation at the same time ejecting the contained air. 

The excellence of the system depends in the greatest measure 
on good design and the employment of special facilities that 
allow all water to be discharged from the radiators and returned 
to the boiler without accumulation at any part of the circulating 
system. It requires, further, the discharge of the air from the 
system at atmospheric pressure. The system is, therefore, prac- 
tically pressureless. 

Various systems of vapor heating are sold under the names 
of their manufacturers. Each possesses special appliances for 
producing positive circulation that are advocated as features of 
particular excellence. The vapor system of heating has met with 
a great deal of favor as a more nearly universal form of heating 
than either the pressure-steam plant or the hot-water method of 
heating. 

Fig. 31a is a diagram illustrating the C. A. Dunham system 
of vapor heating. It will be noticed that there are no air vents 
on the radiators. The air from the radiators is ejected through 
a special form of trap that is indicated in the drawing. These 
traps permit the water and air to pass from the radiators but 
close against the slightly higher temperature of the vapor. This 
assures the condensation of the vapor in the radiators and ex- 
cludes it from the return pipes. The water returns to the boiler 
in much the same manner as in the pressure systems already de- 
scribed but the air escapes through the air eliminator as indi- 
cated in the drawing. The system is, therefore, under atmos- 



THE STEAM HEATING PLANT 



35 



pheric pressure at this point and only a slight amount greater 
in the boiler. 

The water of condensation is returned to the boiler against 
the vapor pressure, by a force exerted by the column of water 
in the pipe connecting the air eliminator with the boiler. The 




Fig. 31a. — Diagram showing the C. A. Dunham Co.'s system of vapor heating. 

main return is placed 24 inches or more above the water line of 
the boiler. It is the pressure of this column that forces the 
water into the boiler through the check valve, against the vapor 
pressure in the boiler. 



36 MECHANICS OF THE HOUSEHOLD 

It might be imagined that the water in the boiler and that 
in the air-ehminator pipe formed a '^U-tube/' the vapor pressure 
on the water surface in the boiler, and the atmospheric pressure 
on the water in the eliminator standpipe. The slight vapor pres- 
sure in the boiler is counterbalanced by a column of water in the 
eliminator pipe. It is this condition that fixes a distance of 24 
inches from the water line to the return pipe; that is, the force 
exerted by a column of water 24 inches high is required to send 
the water into the boiler. 

The vapor pressure is controlled by means of the pressurestat, 
which is an electrified Bourdon spring pressure gage, connected 
up by simple wiring to the damper motor, which may be any form 
of damper regulator. In residential work, the pressurestat is so 
connected with a thermostat, that both pressure and temperature 
conditions operate and control this damper regulator, which in 
turn controls the draft and the fire. 

The two instruments are so connected that if the pressure 
mounts to 8 ounces and the pressurestat caused the draft damper 
to close and the check to open, the thermostat cannot reverse 
the damper, regardless of the temperature in the room, until 
the pressure drops below the limiting 8-ounce pressure. Just 
so long as the pressure is below 8 ounces, the thermostat is the 
master in the control of the dampers. The minute that the 
pressure goes up to 8 ounces then the pressurestat takes control. 



CHAPTER II 
THE HOT-WATER HEATING PLANT 

Of the various systems of heating dwelhngs that by hot-water 
is considered by many to be the most satisfactory. On account 
of its high specific heat, water at a temperature much below the 
boiling point furnishes the heat necessary to keep the tempera- 
ture of the house at the desired degree. The temperature of 
the radiators is generally much lower than those heated by 
steam but the amount of radiating surface is greater than for 
steam heating plants of the same capacity. It is because of 
the relatively low temperature at which the water is used, that 
the greater amount of heating surface is required. 

One objection to the use of hot water as a means of heating 
is, that once the heat of the house is much reduced, the furnace 
is a long time in raising the temperature to normal. This is 
due to the fact that the temperature of the water of the entire 
system must be uniformly raised, because of its continuous pas- 
sage through the heater. On the other hand, this uniformity 
of the temperature of the water prevents sudden changes in 
the temperature of the house. Water-heating plants work with 
perfect quiet and may be so regulated to suit the outside tem- 
perature that the heat of the water will just supply the amount 
to suit the prevailing conditions. 

The care required in the management of the boiler is less 
than that required in the steam plant because of the fewer 
appliances necessary for its safe operation. Another advantage 
in the use of the hot-water plant is its adaptability to the 
temperature conditions during the chilly weather of early fall and 
late spring, when a very small amount of heat is required. At 
such times the temperature of the radiators is but a few degrees 
warmer than the outside air. The amount of attention necessary 
for maintaining the proper furnace fire under such conditions is 
less then for any other form of heating. The increasing use of 

37 



38 



MECHANICS OF THE HOUSEHOLD 



the hot-water plant for heating the average-sized dweUing attests 
to its excellence in service. 

The Low-pressure Hot-water System.^ — A hot-water system 
consists of a heater, in which the water receives its supply of 
heat, the circulating pipes for conducting the heated water to 
and from the radiators that supply heat to the rooms, and the 
expansion tank that receives the excess of water caused when the 

temperature is raised from nor- 

HB^pansion ^al *^ ^^^ working degree. In 

Tank addition to the parts named there 

are a number of appliances to 
be described later, that are re- 
quired to make the system com- 
plete. 

A hot-water plant of the sim- 
plest form is shown in Fig. 32. 
The illustration presents each of 
the features mentioned above, 
as in a working plant. The 
different parts are shown cut 
across through the middle, the 
black portion representing water. 
Not only does the water fill the 
entire system but appears in the 
expansion tank when the plant 
is cold. 

Hot-water heaters are quite 
generally in the form of intern- 
ally fired boilers. The fire-box 
occupies a place inside the boiler and is surrounded, except at 
the bottom, by the water space. Commonly, these boilers are 
made of cast iron and are constructed in sections, the same as 
the steam boiler shown in Fig. 16. Manufacturers sell a single 
style for either steam or hot-water heating. The boiler in Fig. 
32 is cylindrical in form. It is made of wrought iron and con- 
tains a large number of vertical tubes through which the heat 
from the furnace must pass on its way to the chimney. 

As the water is heated it expands and rises to the top of the 
boiler because of its decreased weight. Since the water in the 




Fig. 32. — Diagram of a simple form 
of hot-water heating plant. 



THE HOT-WATER HEATING PLANT 39 

radiator is really a part of the same body of water, the heated 
portion rises through the supply pipe to the top of the radiator. 
As the hot water rises in the radiator, it displaces an equal amount 
of cold water, which enters the boiler at the bottom. This 
displacement is constant and produces a circulation that begins 
as soon as the fire is started and varies with the difference in 
temperature between the hot water leaving the boiler at the top 
and the cold water entering at the bottom. 

As the water in the system is heated and expands, there must 
be some provision made to receive the enlarging volume. In 
this arrangement a pipe connects the bottom of the boiler with 
the expansion tank located at a point above the radiator. Under 
the conditions represented in the drawing the water does not 
circulate through the tank and as a consequence the water it 
contains is always cold. 

In raising its temperature, water absorbs more heat than any 
other fluid and on cooling it gives up an equal amount. As 
a consequence it furnishes an excellent vehicle for transmitting 
the heat of the furnace to the rooms to be heated. Water, 
however, is a poor conductor and receives its heat by coming 
directly into contact with the hot surfaces of the furnace, and 
gives it up by direct contact with the radiator walls. To trans- 
mit heat rapidly and maintain a high radiator temperature, 
the circulation of the water in the system must be the best 
possible. The connecting pipes between the boiler and the radi- 
ators must be as direct as circumstances will permit and the 
amount of radiating surface in each room must be sufficient to 
easily give up an ample supply of heat. Even though the furnace 
is able to furnish a plentiful supply of heat to warm the house, 
it cannot be transmitted to the rooms unless there is sufficient 
radiating surface. A plant might prove unsatisfactory either 
because of a furnace too small to furnish the necessary heat or 
from an insufficient amount of radiating surface. Yet another 
factor in the design of a plant is that of the conducting pipes. 
Both the boiler and the radiators might be in the right proportion 
to produce a good plant, but if the distributing pipes are too small 
to carry the water required, or the circulation is retarded by many 
turns and long runs, the plant may fail to give satisfaction. 

Fig. 33 shows a complete hot-water plant adapted to a dwelling. 



40 



MECHANICS OF THE HOUSEHOLD 



It is just such a plant as is commonly installed in the average- 
sized house but without any of the appliances used for auto- 
matic control of temperature. The regulation of the temperature 
is made entirely by hand, in so governing the fire as to provide 
the required amount of heat. In the drawing the supply and 
return pipes may be traced to the radiators as in the case of the 
simple plant. The supply pipe from the top of the boiler branches 
into two circuits to provide the water for the two groups of radi- 
ators at the right and left side of the house. To provide any 




Fig. 33. — The low-pressure hot-water heating system applied to a small dwelling. 

radiator with hot water, a pipe is taken from the main supply pipe 
and passing through the radiator it is brought back and connected 
with the return pipe which conducts the water back to the boiler. 
The expansion tank is located in the bathroom near the ceiling. 
It is connected with the circulating system by a single pipe which 
joins the supply pipe as it enters the radiator located in the 
kitchen. Like the expansion tank in Fig. 31 the water it con- 
tains is always cold. It is provided with a gage-glass which 
shows the level of the water in the tank and an overflow pipe 
which discharges into the bathtub, in case of an overflow. An 
overflow pipe must always be provided to take care of the sur- 



THE HOT-WATER HEATING PLANT 41 

plus when the water in the system becomes overheated. This 
does not often occur bub the provision must be made for the 
emergency. The overflow pipe is frequently connected directly 
with the sewer or discharged at some convenient place in the 
basement. 

The High-pressure Hot-water System. — In the hot-water 
plant described the expansion tank is open to the air and the 
water in the system is subjected to the pressure of the atmosphere 
alone. The heat of the furnace may be sufficiently great to 
bring the entire volume of water of the system to the boihng 
point and cause it to overflow but the temperature of the water 
cannot rise much above the boiling point due to the pressure of 
the atmosphere. 

If the expansion tank is closed, the pressure generated by the 
expanding water and the formation of steam will permit the 
water to reach a much higher temperature. In the table of 
temperatures and pressures of water on page 3, it will be 
seen that should the pressure rise to 10 pounds, that is, 10 pounds 
above the pressure of the atmosphere, the temperature of the 
water would be very nearly 240°F. (239.4°F.). The difference 
in heating effect in hot-water heating plants under the two con- 
ditions is very marked. In the low-pressure system the tempera- 
ture of the radiators cannot be above 212° but the high-pressure 
system set for 10 pounds pressure will heat the radiators to 240°, 
and a still higher pressure would give a correspondingly higher 
temperature. The amount of heat radiated by a hot body is in 
proportion to the difference in temperature between the body 
and the surrounding air. If we consider the surrounding air 
at 60° the difference in amount of heat-radiation capacity of 
the two radiators would be as 180 is to 132. The advantage 
of the high-pressure system lies in its ability to heat a given 
space with less radiating surface than the low-pressure system. 

In Fig. 34 is illustrated an application of a simple and efficient 
valve arrangement that converts a low-pressure hot-water system 
into a high-pressure system without changing in any way 'the 
piping or radiators. The drawing shows the boiler and two 
radiators connected as for a low-pressure system, but attached 
to the end of the pipe as it enters the expansion tank is a safety 
valve B and a check valve A, as indicated in the enlarged 



42 



MECHANICS OF THE HOUSEHOLD 



figure of the valve. The safety valve is intended to allow the 
water to escape into the expansion tank when the pressure in 
the system reaches a certain point for which the valve is set. 
The check valve A 'permits the water to reenter the system 
from the tank whenever the pressure is restored to its normal 
amount. 




B W 


7 




^ 


^. 


if" 1 


^ 



Fig. 34. — The high-pressure system of hot-water heating. 

Suppose that such a system is working as a low-pressure plant. 
The hot water from the top of the boiler is flowing to the radia- 
tors through the supply pipe and the displaced cooler water is 
returning to the bottom of the boiler through the return pipe as 
in the other plants described. It is now found that the radiators 
are not sufficiently large to heat the rooms to the desired de- 
gree except when the furnace is fired very heavily. It is always 



THE HOT-WATER HEATING PLANT 43 

poor economy to keep a very hot fire in any kind of a heater, be- 
cause a hot fire sends most of its heat up the chimney. If the 
radiators could be safely raised in temperature, they would, of 
course, give out more heat and as a result the rooms would be more 
quickly heated and kept at the required temperature with less ef- 
fort by the furnace. The difficulty in this case lies solely in 
there being insufficient radiator surface to supply heat as fast 
as required. 

The increase in radiator temperature is accomplished by the 
pressure regulating valve B, attached to the end of the pipe as 
it enters the expansion tank. The expansion tank with the regu- 
lating valve is shown enlarged at the left of the figure. The valve 
B is kept closed by a weight marked TT, that is intended to hold 
back a pressure of say 10 pounds to the square inch. A pressure 
of 10 pounds will require a temperature of practically 240°F. 
(see table on page 3). The check valve A is kept closed by 
the pressure from the inside of the system. When the pressure 
of the water goes above 10 pounds — or the amount of the weight 
is intended to hold back — the valve is lifted and an amount of 
water escapes through the valve B into the tank, sufficient to 
relieve the pressure. Should enough water be forced out of the 
system to fill the tank to the top of the overflow pipe, the over- 
flow water is discharged through this pipe into the sink in the 
basement. 

When the house has become thoroughly warmed, the demand 
for a high radiator temperature is reduced, the furnace drafts 
are closed, the water in the system cools and as it shrinks the 
system will not be completely filled. It is then necessary to 
take back from the tank the water that has been forced out 
by excess pressure. It is here that the check valve comes into 
use. So long as there is pressure on the pipes, this valve is held 
shut and no water can escape, but as the inside pressure is 
released by the cooling there will come a point where the water 
in the tank will flow back through the valve A and fill the system. 

This is the type of valve used by the Andrews Heating Co. 
and designated a regurgitating valve. In practice it gives ex- 
cellent service. The only danger of excessive pressure in the 
use of this device is the possibiUty of the valve becoming stuck 
to the seat through disuse. Any possible danger from such an 



44 MECHANICS OF THE HOUSEHOLD 

occurrence may be eliminated by the occasional lifting of the 
valve by hand. 

Heating-plant Design. — A heating plant should be designed by 
a person of experience. No set of rules has yet been devised that 
will meet every condition. Carpenter^s rules given on page 25 
serve for hot water as well as for steam as a means of determining 
the radiating surface required for an ordinary building, but the 
rules do not take into account the method of construction of 
the house and the consequent extra radiation demanded for 
poorly constructed buildings. In many cases the designer must 
rely on experience as a guide where the rules will not apply. 
In the case usually encountered, however, the rules given will 
meet the conditions. 

What was said regarding the size of steam boilers required 
for definite amounts of heating surfaces, applies with equal force 
to hot-water boilers, because house-heating boilers are commonly 
used for either steam or hot-water heating. There are no es- 
tablished rules for determining the heating capacities of house- 
heating boilers. Manufacturers' ratings are usually low. There 
are some manufacturers who make honest ratings for their boilers 
but they are in the minority. When the heating capacity of a 
boiler is not known from experience, the only safeguard against 
installing a boiler too small for the radiators to be heated, is 
to require a guarantee that the plant will give satisfaction when 
in operation and when considered necessary a certain percentage 
of the contract price should be withheld until the plant proves 
itself by actual trial. 

Overhead System of Hot-water Heating. — In Fig. 35 is illus- 
trated another system of high-pressure hot-water heating that 
corresponds to the overhead system of steam heating. It differs 
from the high-pressure system already described in the method 
of distribution and in the radiator connections. 

The flow pipe is taken to the attic and there joined to the 
expansion tank as a point of distribution. On the expansion 
tank is a safety valve set at 10 or more pounds pressure. The 
flow of the water is all downward toward the radiators. The 
circulation through the radiators is also different from the other 
plants described. The supply pipe joins directly to the return 
pipe and the connections to the radiators are made at the top and 



THE HOT-WATER HEATING PLANT 



45 



bottom of the same end. The circulation through the radiators 
in this case is due to the difference in gravitational effect between 
the hot and colder water at the top and bottom of the radiator. 
The system requires no air vents on the radiators as all air that 
might collect in the system goes up to the expansion tank. The 
safety valve on the expansion tank in this case is the common 
lever type. The overflow should empty into the sewer and be 
pitched to prevent any water being retained in the discharge 




Fig. 35. — The overhead system of hot-water heating. 



pipe. If water should be retained in this pipe and should freeze, 
the.system would become dangerous, because of the possibility of 
high pressures from a hot fire. 

Expansion Tanks. — Fig. 36 is a form of expansion tank in 
common use. It may be used for either the high- or low-pressure 
system. The body of the tank is made of galvanized iron and 
is made to stand a considerable amount of pressure. The gage- 
glass is attached at fi, and the overflow at 0. The pipe E con- 
nects the tank with the circulating system and D connects with 
the cold-water supply as a convenience for filling the system 



46 



MECHANICS OF THE HOUSEHOLD 



with water. The object in placing the stop-cock D near the 
expansion tank is to avoid overflowing the system in fiUing. 
The overflow pipe, as stated above, is most conveniently con- 
nected with the sewer, into which the water will run in case of 
an overflow, but the other methods shown are commonly used. 
There should be no valve in this pipe nor in the pipe E, 




Fig. 36. — The expansion Fig. 37. — When the expansion tank of a hot- 

tank, water heating system must be so located that 

it is apt to freeze, it must be piped as a radiator. 

The expansion tank must be so located that there will be no 
danger of freezing. Should it be necessary to place the tank in the 
attic or where freezing is possible, the tank must be so connected 
as to become a part of the circulating system. Such an arrange- 
ment is shown in Fig. 37. The expansion tank is connected with 
a supply and return pipe as a radiator. This arrangement is 
sometimes used but it is not desirable. It is wasteful of heat 
and there is always a possibility of freezing in case the fire in 



THE HOT-WATER HEATING PLANT 47 

the furnace is extinguished a sufficient time to allow the water 
to grow cold. 

Any possibility of danger from excessive pressures in either 
the low-pressure or the high-pressure system must originate in 
the expansion tank. It is, therefore, desired to again mention 
the possible causes of danger. Any closed-tank system is liable 
to become overheated. The expansive force of water is irresist- 
ible and unless some means is taken to prevent excessive pres- 
sure some part of the apparatus is apt to burst. No closed- 
tank system should he used without a safety valve. 

The low-pressure or open-tank system requires no safety ap- 
pliances. So long as there is open communication between the 
tank and the boiler the pressure cannot rise but slightly above 
that of the atmosphere. There is only one cause that will lead 
to high pressure in such a system. If the pipe connecting the 
expansion tank is stopped an excessive pressure might generate. 
There is little or no danger of this happening. 

In the closed-tank system the expansion tank should be of 
greater capacity than for the open-tank system. Its size is com- 
monly about one-ninth of the volume of water used. The larger 
tank is necessary to prevent too rapid rise of pressure as the tem- 
perature of the water rises. The air in the tank acts as a 
cushion against which the pressure of the expanding water is 
exerted. 

The extended use of hot-water heating has led to the invention 
of many appliances for the improvement of the circulation and 
heating effects. Pulsation valves are used for retaining the water 
in the boiler until a definite pressure has been attained that will 
lift the valve long enough to dissipate the pressure. Many of 
these systems possess merit and some of them are great improve- 
ments over the simple plant. 

Radiator Connection. — The method of connecting the radiators 
to the distributing pipes depends entirely on local conditions. 
In a well-balanced system any of the methods shown in Figs. 38, 
39 or 40 might be used with good heating effects. The method 
of attaching the supply pipe to the radiator is, however, an im- 
portant factor in case of accumulation of air. In Fig. 41 is 
shown the form of connection most commonly used. The draw- 
ing is intended to represent a cast-iron radiator witli the valve 



48 



MECHANICS OF THE HOUSEHOLD 



at Z), and the air vent at B, Should air collect in the radiator 
it will rise to the top and displace the water. The water will 
continue to circulate and heat as much of the radiator as is in 
contact with the water, but that part not in contact will receive 



[ 



n 



] 



ii 



01 14 



Qi 



] 



] 



m 



Fig. 38. Fig. 39. Fig. 40. 

Figs. 38 to 40. — Various methods of attaching the supply and return pipes to 

hot-water radiators. 

no heat from the water and will, therefore, fail to fulfill its 
function. As soon as the air vent is opened the air will escape 
and allow the water to entirely fill the space. 




Fig. 41. — The effect of accumu- Fig. 42. — With this method of connec- 

lation of air in a hot-water radiator tions, if the air collects sufficiently to force 
with bottom connections. the water down to the level L, circulation 

will stop. 

In Fig. 42 a much different condition exists, when air accumu- 
lates. In this mode of connection the water enters through the 
valve y, and escapes at the bottom of the opposite end. When 
air fills the radiator to the line L, the circulation is stopped and 
the radiator will grow cold. 



THE HOT-WATER HEATING PLANT 



49 



The position of the Valve on these radiators is of Uttle conse- 
quence. The valve is intended merely to interrupt the flow of 
the water and may occupy a place on either end of the radiator 
with the same result. 

Hot-water Radiators. — Radiators for hot-water heating are 
most commonly of cast iron and in appearance are the same as 
those used for steam heating. The only difference in the two 
forms is in the openings between the sections. Those intended 
for steam have an opening at the bottom joining the sections; 
while those for hot water have openings at both top and bottom 
to permit circulation of the water. 

Hot- water Radiator Valves. — Valves for hot-water radiators 
differ materially from those used on steam radiators. Figs. 43 





Fig. 



43. — The hot-water radia- 
tor valve. 



Fig. 43o. — Details of con- 
struction of the hot-water 
radiator valve. 



and 43a show the outside appearance and the mechanical arrange- 
ment of the parts of the Ohio hot- water valve. The part A in 
Fig. 43a is a hollow brass cylinder attached to the valve-stem, 
one side of which has been removed. When it is desired to shut 
off the supply of heat the handle of the valve is given one-quarter 
turn and the part A covers the opening to the inlet pipe. The 
supply of water being shut off, the radiator gradually cools. 
When the valve is closed a small amount of water is admitted to 
the radiator through a >^-inch hole in the piece A to prevent the 
possibility of freezing. 

Air Vents. — In the use of the systems of hot-water heating 
described, every radiator must be supplied with an air vent of 
some kind to take away the trapped air which accumulates 
through use. Any kind of a valve will serve as a vent for hand 



50 MECHANICS OF THE HOUSEHOLD 

regulation and generally such a cock as is shown in Fig. 10 is 
employed. 

Automatic Hot-water Air Vents. — It is sometimes desired to 
use automatic air vents on hot-water radiators. For such work 
a vent is used that remains closed as long as water is present and 
will open when the water is displaced by the accumulating air, 
but will again close when the air is discharged. In such vents 
the valve is controlled by a float, the buoyancy of the float when 
surrounded by water serving to keep the valve closed. These 
vents are not so positive in their action as automatic air vents 
for steam. The change in temperature which controls the steam 
vent does not take place with hot water. The automatic hot- 
^ water vents are not perfectly reliable. They 

\l ^ may work with entire satisfaction for a long time 
>^JIf:^ and then fail from very slight cause. The failure 
of a hot- water vent is generally discovered by find- 
ing a pool of water on the floor or a wet spot on 
j, I the ceiling or wall of the floor below. 
^^mjUa i 0^^ type of the automatic hot- water vent that 

_" has proven quite successful is shown in Fig. 44. 
The threaded lug is screwed into the radiator at 
tomatic airvent ^^^ proper point. As the water enters the radia- 
for hot-water ra- tor the air is discharged through the vent, escap- 
ing at the opening C. When the water has risen 
to a sufficient height it enters the openings G and H until enough 
is present to raise the float A. The pointed stem attached closed 
the hole C with sufficient force to make an air-tight joint. The 
float A is a very light copper cylinder. Its buoyancy supplies 
the force to close the vent and its weight opens the vent when 
the water is displaced by air. It will be readily seen that very 
slight cause might prevent the performance of its duty. 



CHAPTER III 
THE HOT-AIR FURNACE 



Of the methods of heating dwellings other than by stoves, that 
of the hot-air furnace is the most common. Of the various modes 
of furnace heating it is the least expensive in first cost and most 
rapid in effect. In the use of steam heat, the water in the boiler 
must be vaporized before its heat is available. With hot-water 
heating, the whole mass of water in the entire system must be 
raised considerably in temperature before its heat can affect the 
temperature of the rooms, and consequently in first effect it is 
very slow. In the use of the hot-air furnace the heat from the 
register begins to warm the rooms when the fire is started. 

Hot-air furnaces are made by manufacturing companies in a 
great variety of styles and forms to suit purposes of every kind. 
In practice the furnace is built in sizes, to heat a definite amount 
of cubical space. The maker designs a furnace to heat a certain 
number of cubic feet of space contained in a building. It must 
be sufficiently large to keep the temperature at 70°F. on the 
coldest nights of winter when the wind is blowing a gale. It is 
evident that with the variable factors entering the problem, the 
designer must be a person of experience in order that the furnace 
meet the requirements. 

The following table taken from a manufacturer's catalogue 
shows the method of adapting the product of the maker to any 



Furnace number 


1 


2 


3 


4 


5 






Weight without casing, lb. 


984 


1,111 


1,340 


1,531 


1,934 


Estimated capacities in 
cubic feet 


8,000 

to 
12,000 


12,000 

to 
20,000 


20,000 

to 
35,000 


35,000 

to 
60,000 


60,000 

to 
100,000 






Capacity in number of 
rooms of ordinary size in 
residence heating 


3 to 5 


5 to 7 


7 to 9 


9 to 12 


12 to 15 



51 



52 



MECHANICS OF THE HOUSEHOLD 



size of dwelling. The volume of the house is calculated in cubic 
feet and from this result the size of furnace most nearly suited 
is selected from the table. 



CONSTRUCTION 

The furnace, in general construction, consists of a cast-iron 
fire-box with its heating surfaces, through which the flames and 
heated gases from the fire pass, on the way to the chimney; these 
with the passages and heating surfaces for heating the air compose 

the essential features. Fig. 45 
shows such a furnace with the 
sides broken away to show the 
internal construction. The 
flames and gases from the fire- 
box F circulate through the cast- 
iron drum D and are discharged 
at C to the chimney. The drum 
D is made in such form that it 
presents to the heat from the 
fire a large amount of heating 
surface and at the same time 
offers as little opposition as 
possible to the furnace draft. 
The air to be heated enters the 
furnace through the cold air duct 
at the bottom, and after circu- 
lating through the drum, passes 
out at the openings R to the conducting pipes. The cast-iron 
box TF is a water tank that should be attached to every hot-air 
furnace. The water contained in the tank is for humidifying 
the air as it passes through the furnace. In this furnace the 
outside casing is of sheet iron, reinforced with wrought-iron 
flanges. The front, which contains the doors of the fire-box, 
ash-pit, etc., are of cast iron of ornamented design. 

As the air to be heated passes through the furnace it receives 
part of its warmth by radiation but most of it is absorbed by 
coming directly into contact with the heating surfaces. Since air 
is a poor conductor of heat its temperature is raised very slowly; 




Fig. 45. — Interior view of a hot-air 
furnace. 



THE HOT-AIR FURNACE 53 

it should, therefore, be kept in contact with the heating surfaces 
as long as possible to insure an economical furnace. In common 
practice the ratio of heating surface to grate surface average 35 
to 1; that is, for each square foot of grate surface there is 35 
square feet of heating surface to warm the passing air. Should 
this ratio be increased to 50 to 1 the efficiency of the furnace 
would be much improved. 

If the ratio of heating surface to the grate surface is too small 
for its requirements, the temperature of the air-heating surfaces 
must be very high to provide the desired amount of heat. Under 
such a condition the efficiency of the furnace would be low, since 
in all cases where rapid combustion is required the available 
amount of heat per pound of coal consumed is low. With a 
large amount of heating surface, the air remains in contact with 
the hot surface a relatively longer period and the desired tempera- 
ture is reached with the expenditure of a smaller amount of fuel. 
A momentary exposure of the air to a red-hot surface is far less 
effective than a prolonged contact with a surface having only a 
moderate temperature. Time is an element of great importance 
in heating air. In considering the relative merits of two furnaces 
with the same amount of grate surface, that with the larger 
amount of heating surface will evidently be the most efficient. 

The supply of heat comes primarily from the burning coal on 
the furnace grate. The grate surface should be large enough in 
area to permit the required quantity of heat to be generated by 
the burning fuel with a moderate fire. If the grate surface is too 
small for the required purpose, a hot fire will be necessary, when 
the normal amount of heat is demanded by the house. During 
extremely cold weather, particularly when accompanied by high 
wind, the extra heat demanded to keep the house at the desired 
temperature makes necessary the use of an amount of fuel that 
cannot be burned on the grate unless the fire is forced. Hot fires 
can be kept up only at the expense of a large amount of heat, and 
the resultant efficiency of the furnace is reduced. 

High furnace temperatures are always attended by a large 
loss of heat. The vastly greater quantity of air necessary to 
create the combustion, the high temperature of the chimney gases 
and the increased velocity of the heated gases through the 
furnace, all tend to increase the amount of heat that is sent up 



54 MECHANICS OF THE HOUSEHOLD 

the chimney, and to decrease the percentage of heat that 
is delivered by the furnace. In order to heat the house eco- 
nomically the furnace must be large enough to easily generate 
the required amount of heat demanded in the most severe 
weather. 

Furnace-gas Leaks. — The presence of furnace gas in the atmos- 
phere of a house is not only annoying but may be a source of 
danger. Gas leaks are commonly due to the imperfect union of 
the various parts of which the furnace is composed. 

Cast-iron furnaces are constructed in sections that are as- 
sembled to form a complete plant. In assembling, the various 
parts of contact must be carefully joined to prevent the gases in 
the fire-box from escaping into the air-heating space. In the 
manufacture of cast-iron furnaces it is practically impossible to 
form gas-tight joints by the contact of the metal alone. In the 
erection of the furnace all doubtful joints are filled with stove 
putty. Furnaces of good design require the use of the least 
amount of this material. 

Stove putty is composed of finely divided graphitic carbon 
that is made into a paste suitable for filling all imperfect joints. 
When the putty hardens it withstands the heat to which it is 
subjected, without shrinking. In the course of time, however, 
the putty may be displaced and leave openings through which 
the furnace gases may leak into heating space and thus enter the 
house. Leaks of the kind may be stopped by renewing the putty 
which may be obtained from any dealer in stoves. 

Location of the Furnace. — The location of the furnace will 
generally be governed by the exposure of the house and the 
location of the chimney. In all exposed rooms on the windward 
side of the house the temperature will be lower and the air pres- 
sure higher than in other parts of the house. The increase in 
atmospheric pressure makes it necessary to supply to such rooms 
the hottest air practicable. The conducting pipes, therefore, 
should be most directly connected with the furnace and with the 
least run of horizontal pipe. The proper place for the furnace 
is as near as possible the coldest place of the house. 

It is a common practice to place registers near the inner corner 
of the room, in order to economize in conducting pipe, in hori- 



THE HOT-AIR FURNACE 



55 



zontal runs. A small amount of economy in first cost is thus 
secured but the efficiency of the apparatus is sacrificed. 

The greatest objection to placing the registers and conducting 
pipes in the outer walls of buildings is that of loss of heat, due 
to exposure to the outside cold and the resulting loss in circula- 
tion. Losses of this kind may be prevented by covering the 
ducts with the necessary non-conducting material. The regis- 
ters should occupy a place in the room 
nearest the entering cold air. 

Flues. — ^It is customary to place the 
conducting pipes for the first floor in 
such a way as to use only the shortest 
connections. The flues used for the 
second floor produce, as in a chimney, 
a greater velocity of flow to the air 
and as a consequence larger horizontal 
pipes are used at the furnace. All 
horizontal pipes should have upward 
slant, as much as the basement will 
permit. 

The velocity of the air in the con- 
ducting flues will depend on two fac- 
tors : • the height of the flue, and the 
temperature of the air. To prevent 
the loss of the temperature of the air, 

the flue should be covered with at least fig. 46.— Method of con- 
two layers of asbestUS paper bound with ducting warm air from the fur- 
^TT n ri 1 n i nace to the registers. 

Wire. Wall flues are commonly flat- 
tened and occupy a place in the wall between the studding. 
Each flue should have a damper at the furnace, that will per- 
mit the heat to be shut off from any part of the house. 

Rules for proportioning of registers and conducting flues to 
suit rooms of various sizes are entirely empirical. The sizes 
of registers and flues found satisfactory in practice is generally 
a guide for the designer. The following table is taken from a 
manufacturer's catalogue and gives a list of sizes that have proven 
satisfactory under a great variety of conditions and may be 
taken as good practice: 




56 



MECHANICS OF THE HOUSEHOLD 





First Floor 




Sizes of registers 
in inches 


Dianieter of pipes 
in inches 


Size of rooms 
in feet 


Height of ceilings 
in feet 


12 by 15 

10 by 14 

9 by 12 

8 by 12 


12 

10 

9 

9 


18 by 20 
15 by 15 
14 by 15 
13 by 13 


11 

10 

9 

9 



Second Floor 



10 by 14 


10 


18 by 20 


10 


9 by 12 


9 


16 by 16 


9 


8 by 12 


8 


13 by 13 


8 


8 by 10 


7 


12 by 12 


8 



The furnace is not only a means of heating the hosne but may 

be a means of ventilation as 
well; to this end it is desir- 
able to arrange the air supply 
of the furnace to connect with 
the outside air. This arrange- 
ment assures a supply of 
oxygen even though no special 
means is arranged for dis- 
charging the vitiated air from 
the rooms. 

Combination Hot-air and 
Hot-water Heater. — In the 
case of large houses heated 
by hot air it is sometimes 
better to use two or more 
furnaces than to attempt to 
carry the heat long dis- 
tances in the customary 
pipes. Where heat is re- 
quired in rooms located at a 
distance more than 30 feet, it is advisable to use a combination 
hot-air and hot-water heater, the distant rooms being heated 
by hot- water radiators. 

A furnace arranged for such a combination is shown in Fig. 47. 




Fig 47. — Interior construction of a com- 
bination hot-water and hot-air furnace. 



THE HOT-AIR FURNACE 



57 



This furnace contains, first, the essential features of a hot-air 
furnace; next, it includes a hot- water plant. The fire-box and 
air-heating surfaces are easily recognized. The arrows show the 
course of the air entering at the bottom of the furnace, which 
after being heated by passing over the heating surfaces, escapes 
at the openings marked warm air, to the distributing pipes. 

Inside the air-heating surfaces are three hollow cast-iron pieces 
TF, that form a part of the walls of the fire-box. These pieces, 
with their connecting pipes, form the water-heating part of the 




The hot-air furnace as it appears in the house. 



furnace, which supplies the hot water for the radiators. The 
pieces W, with the connecting pipes and radiators, form an in- 
dependent heating plant, with a fire-box in common with the 
hot-air furnace. 

The returning water from the radiators enters the heating 
surfaces W, through the pipe marked return pipe. The heated 
water is discharged from the heaters into that marked flow pipe 
which conducts it to the radiators. Such a furnace is, therefore, 
two independent systems, one for hot air and the other for hot 
water, but with a single fire-box. This furnace, like the simple 
hot-air furnace, is rated, first in the amount of space it will heat 



58 



MECHANICS OF THE HOUSEHOLD 



with hot air and in addition, by the number of square feet of 
hot-water radiating surface that will be kept hot by the hot- 
water heater. 

In Fig. 48 is shown the location of the furnace in a cottage 
with the conducting pipes to the various rooms. The registers in 
the first floor are generally set in the floor but if desired they 
may be placed in the walls. Those on the second floor are placed 
in the walls because of convenience. The conducting pipes pass 
through the partitions between the studding. 




Fig. 49. — Details of air ducts and damper regulator used with the hot-air furnace . 

In all well-arranged hot-air heating plants provision is made so 
that the air for heating may be taken from the outside. It does 
not follow that the supply of fresh air should always come from 
outdoors; there are times during extremely cold weather, ac- 
companied by high winds, when ventilation is ample without the 
outside source of supply. Since it is never desirable to take the 
air supply from the basement, such an arrangement as is shown 
in Fig. 49, or a modification of the same plan is commonly em- 
ployed. The duct A from the outside and B from the rooms 
above connect with the air supply for the furnaces. A damper C 
arranged to move on a hinge, is so placed as to admit the air from 
either source as desired. The damper may be placed so as to take 
part or all of the air from the outside by adjusting the handle at 
the proper place. 



CHAPTER IV 
TEMPERATURE REGULATION 

The method used for regulating the temperature of a house 
will depend on its size, the conditions under which it is to be used 
and the method of heating. In small houses the temperature 
may be satisfactorily governed entirely by hand, that is, the 
furnace drafts may be changed by hand to suit the varying 
conditions of temperature. A more satisfactory method is that 
of thermostatic regulation, in which a thermostatic governor and 
a motor automatically control the furnace dampers so as to keep 
a constant temperature at one point, generally the living room. 
Where hot-water or steam heating plants are used, another device 
is frequently employed to keep the temperature of the heat supply 
at a constant degree. This is known as the automatic damper 
regulator. The damper regulator is one of the boiler accessories 
which so governs the drafts of the furnace as to keep a constant 
water temperature in the hot-water heater or a constant steam 
pressure in the steam boiler. 

In some cases both the damper regulator and the thermostat 
are used as a more complete means of temperature control. 

Hand Regulation. — As a means of changing the dampers of the 
furnace from the floor above, to suit the prevailing conditions, 
the arrangement shown in Fig. 49 does away with the necessity 
of a journey to the basement, to remedy each change of 
temperature. 

A plate is fastened to the wall at any convenient place, to 
which the end of a chain is attached as shown in the figure. 
This connects with a second chain, the ends of whioh are fastened, 
one to the direct draft or ash-pit damper F, and the other to the 
check draft E^ in the chimney. As the furnace appears in the 
drawing, the direct draft is closed and the check draft is open. 
By changing the ring from G to if, the movement of the chain 
opens Fj and closes -EJ, admitting air to the furnace. When the 

59 



60 



MECHANICS OF THE HOUSEHOLD 



temperature of the room is raised sufficiently, the drafts are re- 
stored to their original position by replacing the ring at (z. 
Sometimes one or more intermediate points are made on the plate 
between and H, which permits both drafts to be kept partly 
open and fewer changes are required to keep the temperature 
approximately normal. 

Damper Regulator for Steam Boiler. — The damper regulator 
used on a steam boiler is a simple device that automatically 
controls the draft dampers by reason of the changing pressures 
of the steam. The object of the damper regulator is to prevent 
the generation of steam in the boiler beyond a certain pressure 
at which the valve is set. This point is usually 3 or 4 pounds 





Fig. 50. — Cross-section of damper 
regulator for steam boiler. 



Fig. 51. — Steam boiler for house 
heating, with the damper regulator, 
in place, attached to the dampers. 



below the pressure at which the safety valve would act. If in 
proper working order the damper regulator will so control the 
dampers that the boiler will always contain a supply of steam, 
but the pressure will not reach a point requiring the action of the 
safety valve. Fig. 51 illustrates its connections with the furnace 
dampers. In Fig. 18 the regulator appears at D. In external 
appearance and in operation of the dampers, it is the same as the 
regulator for a hot-water boiler but its internal construction is 
simpler. Fig. 50 shows its construction. It is attached to the 
steam space of the boiler at E, The steam pressure acts directly 
on the flexible metallic diaphragm B, As the pressure of the 



TEMPERATURE REGULATION 



61 



steam approaches the desired amount the diaphragm is raised 
and with it the lever 7. A chain D, attached to the end of the 
lever, opens the check draft, and another at C closes the draft 
damper. When the steam pressure falls, the diaphragm lowers 
the lever and the dampers are restored to their original position. 
The same movements are repeated with each rise and fall of the 
steam pressure. 

Damper Regulators for Hot-water Furnaces.— The damper 
regulator for a hot-water boiler automatically controls the 
dampers of the furnace so as to keep the water of the boiler 
approximately at a constant temperature. The regulator is 
shown in Fig. 52. The ends of the lever are connected to the 
direct-draft and check-draft dampers, as in the case of the 




Fig. 52. — Damper regulator for hot-water boiler. 

damper regulator for the steam plant. A cross-section of the 
working parts shows the details of construction. The lever d is 
operated by a diaphragm g, which tightly covers a brass bowl, 
containing a mixture of alcohol and water, of such proportions 
as will produce a vapor pressure at the desired temperature, 
say 200°. The hot water from the boiler passes through the 
valve, entering at a and leaving at h. When the water reaches 
the desired temperature, the contained Uquid vaporizes and a 
pressure is produced that is sufficient to hft the diaphragm and 
the lever. The chain attached to the right-hand end closes the 
direct-draft damper; at the same time the other end of the lever 
opens the check draft, and the supply of air to the furnace fire 
is entirely cut off. As soon as the water has cooled sufficiently, 



62 MECHANICS OF THE HOUSEHOLD 

the vapor pressure in the bowl is reduced, allowing the weight 
W to depress the diaphragm and the lever is restored to its first 
position. The weight W is for adjusting the valve to the desired 
temperature. The plug / tightly closes the orifice through which 
the liquid is introduced into the bowl. 

The object of the damper regulator on a hot- water boiler is 
to govern the fire of the furnace so as to keep the water in the 
boiler at the desired temperature. In case there is a demand 
for heat at any part of the house, a supply of hot water will 
always be on hand. It has nothing to do with the regulation 
of the temperature of the house. The control of the house 
temperature is the office of the thermostat. 

The thermostat is a mechanical device for automatically regu- 
lating temperature. It may be arranged to operate the valve 
of a single radiator or register and so control the temperature of 
a room, or as commonly used in the average dwelling, the con- 
troller may be placed to govern the temperature of the living 
room and in so doing keep the furnace in condition to satis- 
factorily heat the remainder of the house. 

Thermostats are made in a variety of forms by different 
manufacturers but they may be divided into two general classes : 
the electric, and the pneumatic types. The electric thermostat 
depends on an electric current as a means of controlling the 
action of the motor which in turn operates the furnace dampers 
so as to maintain a constant heat supply. The pneumatic 
thermostat regulates the supply of heat by means of pneumatic 
valves. It will be considered later in discussing mechanical 
ventilation. This type of temperature regulation is particularly 
adapted to large buildings. 

Fig. 53 illustrates one style of electric thermostat that is very 
generally used for temperature regulation in the average dwelling. 
It consists of three distinct parts — the controller, the electric bat- 
tery and the motor. In the drawing the motor is shown connected 
with a steam valve, such as may be used for furnishing steam 
for a series of radiators. It may with equal facility be attached 
to the dampers of a furnace or other heating apparatus. 

The controller occupies a place on the wall of the room to be 
heated and makes electric connections between the battery and 
the motor. Whenever the temperature varies from the required 



TEMPERATURE REGULATION 63 

degree, a change of electric contact in the controller starts the 
motor, and the radiator valve or the furnace drafts are opened 
or closed as occasion requires. 

The controller appears in Fig. 54 as commonly seen in use. 
The upper part carries a thermometer and the pointer A indicates 
the temperature to be maintained in the room. The middle 
division indicates 70°F. Each division to the right of the middle 
point raises the temperature 5°. Each division to the left lowers 
the temperature a like amount. 

In addition to the ordinary type this controller is furnished 
with a time attachment by means of which the controller may 
permit the temperature of the room to fall to any desired degree 
at night and raise it again in the morning at the time for which 
it is set. 

This is accomplished by a little alarm clock shown at the 
bottom of the controller in Fig. 54. The indicator B is arranged 
to correspond with the indicator A ; the middle point representing 
70°F. To set the time attachment, the alarm is wound and set 
as in any alarm clock, 3-^ hour earlier than the desired time for 
rising. The indicator B is set for the day temperature and A is 
set for the temperature desired during the night. At the 
appointed time the alarm moves the indicator A to the desired 
point for the day and the controller raises the temperature 
accordingly. 

Fig. 55 shows the mechanism that is exposed to view when the 
cover of the controller is removed. The bent strip C is the part 
that is influenced by the change of temperature. It is made of 
two thin strips of metal, one of brass and the other of steel. The 
two strips are soldered firmly together. Any change in tempera- 
ture will affect the strip and cause it to bend and touch the 
contact point — K or J. The bending of the strip is due to 
the unequal expansion of the brass and steel due to the 
change of temperature. Brass expands 2.4 times as much as 
steel with the same change of temperature. The amount of 
bending is sufficient to make an appreciable movement in a small 
fraction of a degree change. The brass part of C is on the left 
and since it expands the greater amount, a rising temperature 
causes C to come into contact with the point J. When this 
happens the motor is started and makes one-half cycle. In so 



64 MECHANICS OF THE HOUSEHOLD 

doing it shuts off the air supply of the furnace, opens the check 
draft and at the same time the motor changes the electric contact 
from J to K. When the temperature begins to fall, the brass con- 
tracts in the same ratio to the steel as it expands during the 
rising temperature and as a consequence the bar bends to the 
left. When the strip touches the point K the motor again makes 
one-half circle, admitting air once more to the furnace, closes 
the check draft and shifts the electric contact back to K, When 
properly started the thermostat will regulate the temperature 
within a degree of temperature. 

The Thermostat Motor. — The thermostat motor automatically 
opens and closes the furnace dampers or the valve that admits 
steam to the radiators as heat is demanded by the controller. 

The motor, as shown in Fig 53, consists of a system of gears 
and a brake >S, which regulates the speed, a cam M, and armature 
7, for starting and stopping the motor, and the electromagnet]i?-7f 
which operates the bar 7. Two lever arms L, one in front and 
the other at the back of the motor furnish means for attachment 
to the valve or furnace dampers. An emergency switch at D 
is shown in detail in Fig. 56. The battery B furnishes the cur- 
rent which energizes the magnets and an iron weight supplies the 
motive power for the motor. 

The description of the operation of the motor applies to the 
steam valve shown in Fig. 53. The same motor might be used 
for opening and closing of the dampers of the furnace in any kind 
of heat supply. The method of communicating the motion of 
the motor arms to the dampers of the furnace will be described 
later. The connections with the furnace drafts are shown in 
Figs. 3, 6, 8, 34, etc. 

Suppose that the valve for admitting steam to the radiators, 
as that in Fig. 53, is closed and that the temperature of the house 
is falling. The strip C of the thermostat controller is moving 
toward J, When contact is made, the current from the battery 
B energizes the magnets H-H and the bar 7 is lifted. As the 
bar 7 is raised the catch J is released and permits the motor to 
start. The bar 7 is held suspended by the cam M until the arm 
L has made one-half revolution, when the lug K drops into the 
depression in the cam made to receive it and the catch J engages 
with the brake and stops the motor. 



TEMPERATURE REGULATION 



65 





Fig. 53. — Thermostat complete with the regulator, battery and motor, attached 
to a steam supply valve. 
5 



66 



MECHANICS OF THE HOUSEHOLD 



During this movement the arm L has Hf ted the valve arm N and 
the valve admits steam to the radiators, at the same time the con- 
tact M has been shifted from the right-hand contact to the left, 
and the electric circuit is ready to be made in the controller at the 
point K, When the temperature has fallen a sufficient amount 
the controller bar C will make contact at K 
and the motor will again make a half cycle, 
changing the valve back to its original posi- 
tion. This process will be kept up so long 
as the motor is wound and there is sufficient 
fuel in the furnace to raise the temperature. 
Fig. 55 shows the method of connecting the 
electric wires from the battery to the con- 
(g^ 30 M ^ troller. A three-wire cable connects the 
battery, and makes contacts as indicated at 
Hj K and J. The wires are shown attached 
to the motor as in Fig. 55. A wire is taken 
from either pole of the battery and attached 
to one of the ends of the magnet coil. Pass- 
ing through the magnet the wire is attached 
to the frame of the motor. This makes the 
cam M a part of the electric circuit. The 
other two wires are attached to the brass 
strips on each side of the arm L. The strips 
are insulated from the frame. The electric 
circuit through the magnet is made alter- 
nately by contact with the strips at right 
and left of the arm L. 

In case the motor, through neglect, runs 
down, a safety switch at D (Fig. 53) discon- 
nects the battery and keeps it from being dis- 
charged. This switch is shown in detail in 
Fig. 56. When the weight has reached its 
limit, the piece C on the chain comes into 
contact with D and lifting it out of contact, breaks the circuit. 
When the motor is again wound, C engages with E and restores 
the contact. The switch is so arranged that when open, the valve 
will always be closed. 




Fig. 54. — Thermo- 
static regulator with 
clock attachment for 
control of day and 
night temperature. 



TEMPERATURE REGULATION 



67 



Gombined Thermostat and Damper Regulator. — It is evident 
that, in heating a house by steam, the damper regulator governs 
only the steam pressure of the boiler. In the use of a thermostat 
alone, the regulation is that of the temperature of the rooms only, 
and has nothing to do with the steam pressure. As an example: 
Suppose that in cold weather the house is cold and that the gage 
of the steam boiler shows no pressure. The desire is to get up 
steam as soon as possible. In so doing a hot fire is made with a 
large amount of fuel. As soon as the steam begins to form, the 
pressure rises rapidly. When the radiators have become hot and 
the steam is no longer taken away as fast as it is formed, the pres- 





FiG. 54 A. — Showing the clock 
attachments to the thermostatic 
regulator. 



Fig. 55. — Mecha- 
nism of the thermo- 
static regulator. 



sure of the steam in the boiler keeps on rising. The thermostat 
will not close the furnace dampers until the temperature of the 
rooms is normal. This may require so great a length of time 
as to produce a great excess of steam that cannot be used at the 
time and the pressure will be relieved by the safety valve. This 
may not be dangerous but it is disagreeable. To prevent the 
safety valve from blowing except in case of emergency, a com- 
bined thermostat and draft regulator is used. In such a com- 



68 



MECHANICS OF THE HOUSEHOLD 



bination, the draft regulator closes the draft as soon as the pressure 
reaches the desired point, after which the thermostat does the 
regulating according to suit the temperature of the house. 

In Fig. 2 is shown such a combination attached to a boiler. 
The cord from the regulator, instead of extending directly to the 
direct-draft damper, passes over the pulley P and connects to the 
thermostat cord. The regulator may now close the damper to 

suit the steam pressure, but after .the 
temperature in the rooms is normal, the 
amount of heat necessary to maintain 
the desired degree is regulated entirely 
by the thermostat which opens and closes 
the dampers regardless of the position 
of the damper regulator. 

If occasion should require but a very 
slight amount of steam to keep the 
house at the desired temperature, the 
thermostat will govern the drafts aright. 
If the steam pressure is in danger of be- 
coming excessive, the damper regulator 
will govern the drafts. 

Thermostat-motor Connections. — The 
arrangement of cords and pulleys used 
for attaching the thermostat motor to 
the furnace dampers will depend very 
much on local conditions. The motor 
can be placed in any convenient position 
so that the connecting cords wilt act 
most directly. The motor opens and 
closes the direct draft and check draft 
in accordance with the demand for heat. The connections for 
all kinds of furnaces are made in much the same manner. The 
pulleys suppHed with the motor are placed to work as freely, and 
the cords to pull as directly as possible. 

In Fig. 57 the motor is connected with a hot-air furnace. The 
cord D is attached to the front arm of the motor and connects 
with the direct-draft damper F. The cord C connects the rear 
arm of the motor with the check-draft damper at E, In the 
position of the dampers shown, the direct-draft damper is closed 




Fig. 5 6 . —A utomatic 
switch which opens the bat- 
tery circuit when the ther- 
mostat motor weight, 
reaches its limit. 



TEMPERATURE REGULATION 



69 



and the air is entering the chimney through the check draft E, 
While this damper is open there is very httle induced draft to 
supply the fire with air that might leak through the crevices 
around the ash-pit door, but the gases from the furnace are 
completely carried away to the chimney by the air entering at E, 
In Figs. 3, 6, 8, 34, etc., the same motor is connected with the 
furnaces of various other systems of heating. The object is the 




Fig. 57. — Thermostat motor connected with the dampers of a hot-air furnace. 

same in all; when less heat is required, the air supply is cut off 
and the furnace fire subsides; when more heat is demanded the air 
is again admitted to produce greater combustion. The check 
draft is an important feature as it checks the flow of air through 
the furnace regardless of the position of the direct-draft damper. 
Even should the direct draft be left open, the check draft when 
open would destroy in a great measure the supply of air entering 
the furnace. 



CHAPTER V 
MANAGEMENT OF HEATING PLANTS 

The following instructions on the care and management of 
steam and hot-water heating plants is printed with permission 
of the American Radiator Co. They were prepared as a guide 
to the successful operation of the Ideal heating plants but 
apply with equal force to other plants of a similar character. 

General Advice. — No set rules can be given for caring for 
every boiler alike — chimney flues are not alike — some have strong 
draft, some are average and some are weak. There is much more 
difference in the heat-making qualities of coal than is commonly 
known, and it is important that the right size coal for the draft 
be used. These rules apply to most all fuels. A little trying of 
this way or that way of leaving the dampers (when regulators are 
not used) often discovers the better way. It is well to vary from 
the rules a little if any of them do not seem to bring about the 
best results. 

With good, average chimney flue draft and the right kind of 
fuel, these rules will govern the large majority of cases. 

The Economy of Good Draft. — In many cases a boiler with 
sluggish draft will burn more coal than a boiler with good draft. 
In the first case the fuel may be said to ^^rof — in lacking air 
supply the gases pass off unburned. The ^^nagging'' which a 
boiler has to take under these conditions increases the waste of 
fuel. A boiler under sharp, strong draft maintains a clear in- 
tense fire and burns the gases — getting the larger amount of 
heat from the coal. 

General Firing Rules. — 

1. Put but little coal on a low fire. 

2. When adding coal to the boiler, open the smoke-pipe damper (in- 
side the smoke pipe) and close the cold-air check damper. This will 
make a draft through the feed doorway inward and prevent the escape 
of dust or gas into the cellar when the feed door is open to take fuel. 
Put these parts back to their regular places after feeding. 

70 



MANAGEMENT OF HEATING PLANTS 



71 



3. When it can be done, in feeding a large amount of coal (as for 
night) leave a part of the fire or flame exposed, so that the gases may 
be burned as they arise. 

4. When a regulator is not used, learn to use the dampers correctly 
and according to the force of the chimney draft. Learn to use cold-air 
check damper. Often, when closing, the ash-pit draft damper does 
not check the fire enough; opening the cold-air check damper will 




Fig. 57a. — Indicates the general condition of the furnace fire during very cold 
weather. The fuel should fill the fire-pot to C. The ashes should not be allowed 
to accumulate beyond B, on the grate. There should be no more ashes than 
appear at H, in the ashpit. 



check it about right. Increasing or lessening the pressure of a steam 
boiler must be done by changing the weight on the regulator bar. 

5. Carry a deep fire or a high fire; let the live coals come up to tlie 
feed door — even in mild weather when from 4 to 6 inches of ashes 
stand on the grate. 

6. In severe weather give the heater the most careful attention the 
last thing at night. 



72 ^ MECHANICS OF THE HOUSEHOLD 

7. Do not overshake or poke the fire in mild weather; once in a while 
shake enough to give place for a little more fuel. 

8. Do not let ashes bank up under the grate in ash-pit. Grate bars 
are very hardy, but it is possible to warp them with carelessness. Tak- 
ing up the ashes once a day is the best rule, even if but little has fallen 
into the pit. 

9. Keep the boiler surfaces and flues clean; a crust of soot J^ inch 
in thickness causes the boiler to require half as much more fuel than 
when the surfaces are clean. 

10. If convenient, have a water hose to spray the ashes when cleaning 
out the pit. 

1 1 . Attend the boiler from two to four times per day. In mild weather, 
running with a checked fire, morning and night is usually often enough. 
In severe weather, once in early morning, again at mid-day, again at 
five or six o'clock and finally thorough attention at from nine to eleven 
o'clock in the evening. 

12. If, through burning poor coal, the fire pot gets full of ashes, or 
slate and clinkers massed together, the quickest way to get a good 
active fire is to dump the grate and then build a new fire — from the 
kindling up. 

13. If a hard clinker lodges between the grate bars, do not force the 
shaking, but first dislodge the mass with a poker or slicing bar. Then 
the grate will operate without damage. 

Weather and Time of Day. — In severe weather keep the fire 
pot full of coal, and run the heater by the dampers or regulator 
(if one is used). Thoroughly clean the grate twice a day. Let 
the top of the fire in front be level with the feed door sill. Bank 
up the coal higher to the rear. 

In moderate weather there should be from 2 to 6 inches of ashes 
between the live coal and the grate. As the weather grows 
colder keep the grate and the fire pot a little cleaner — sometimes 
it helps to run the poker or slicing bar over it through the clinker 
door. With some fuels this is never necessary. 

Night Firing. — In very cold weather, when the house should be 
kept warm all night, clean the grate well at a late hour — the 
last thing. Clear the bottom of the fire pot of all ashes and clink- 
ers so that the grate is covered with clear-burning, red-hot coals, 
then fill the pot full of fuel. If possible, leave some of the flame 
exposed to burn the gases. Leave the drafts on long enough to 
burn off some*of the gas, then check the heater for the night. 



MANAGEMENT OF HEATING PLANTS 73 

Thus there is plenty of coal to burn during the night and some on 
which to commence early in the morning. Some drafts do not 
make it necessary to leave the dampers on to burn off the gas 
after feeding. 

With the ash-pit draft damper closed and the cold-air check 
damper open at night, but part of the coal is burned and there is 
much of it not burned in the morning. So, by reversing the 
dampers in the early morning the fire starts up quickly and often 
the house may be well warmed before any coal is put into the 
fire pot. 

Some boilers are run the other way— a very poor way. If the 
grate is cleared off in very cold weather and coal added at five 
or six o^clock in the afternoon, by eleven o^clock at night nearly 
one-half of the coal is burned and the grate is covered over with 
a mass of ashes and clinkers. With little coal remaining, to 
shake the grate will quite likely put out the remaining fire; to 
put fresh coal on a low fire reduces further its declining tem- 
perature. The result is a cold house that will grow colder until 
a new fire is started. 

Often in cold weather with this poor way of night firing, it 
takes one or more hours of forced firing to warm the house in the 
morning, and all the coal saved the night before is more than 
used to get the house or building ^^ heated up'' — while the people 
who should be comfortable have to get up, bathe and take break- 
fast in chilly rooms. At no time in the day is heat more wanted 
than about the time of getting up and starting the day. A 
fire well cared, for late in the evening makes a warm house 
all night. And so it follows that it is much easier to add a 
little more heat in the morning. And surely less coal is burned, 
for the forcing of a fire part of the time often overheats, and 
wastes coal. 

First-day Firing. — In the morning of moderate winter weather^ 
with the ash-pit draft damper open, before adding any coal allow 
the fire to brighten up if it seems to be low; then (for such condi- 
tions) spread over a thin layer of fresh coal and set the drafts 
for a brisk fire. After the new fire is well started add as much 
coal as may be necessary to last until next firing. Do not shake 
much if any — just enough to give space for more coal. Then by 
setting the regulator (if one is used), or, by closing the ash-pit 



74 MECHANICS OF THE HOUSEHOLD 

draft damper and opening the cold-air check damper a httle, 
the boiler should keep up its work until the next firing time. 

In severe weather, if the boiler has been attended to at night as 
directed in the section on ''night firing/' the drafts can be turned 
on and the boiler run for half an hour before adding coal. Or, if 
more convenient to give it immediate attention, the grate can be 
thoroughly shaken and enough coal added to last until mid-day. 
Often the cold-air check damper will need to be entirely closed 
and the ash-pit draft damper partly open if the heater is a water 
boiler. If a steam boiler, the regulator should then be set to 
maintain the number of pounds of pressure wanted and so left. 

Other-day Firing. — In severe weather more coal should be 
added about noon, sometimes the draft may be left on for a few 
minutes and then checked. And in such weather it is often well 
to give the boiler further attention at five or six o'clock. In 
severest weather the boiler should not be attended more than 
four times a day; and generally not less than three times. 

Often much coal is wasted by ''nagging'' the fire — poking, 
shaking and feeding it until it becomes "dyspeptic." A sure 
cure is a little common sense in regular feeding, etc. 

Economy and Fuels. — In running many boilers for moderate 
weather better results follow if the grate is not shaken too much or 
too often. Sometimes in moderate weather a body of ashes on 
the grate checks the fire and there is enough heat without a 
useless burning of fuel. Many houses are overheated in moderate 
weather and too much coal burned by running the boiler as for 
zero weather. 

So we repeat — it is not wise to overshake or overfeed a boiler in 
moderate weather. The fire should be in such shape that if a 
change comes at night there is a basis for a good fire to start on. 
When the grate is shaken but once during the 24 hours (during 
moderate weather) late at night is the best time. 

When one stops to think that heating is needed during about 
7 months out of the year, and that a greater portion of this time is 
usually moderate weather when a very little heat is needed, it 
must be seen that the science of running the heater to save coal 
is to apply common sense rules of limiting the feeding and the 
attention in such periods. In severe weather we believe in giving 
the boiler a liberal quantity of fuel regularly and at the right 



MANAGEMENT OF HEATING PLANTS 75 

time. The time to save coal is when there is no need for burning 
it. This is where a great many people make errors in running 
the boiler — in forgetting to ''let up'' on the shaking and feeding 
in moderate weather. 

With some drafts and for boilers using hard coal or coke, good 
economical results often are secured by opening the feed door a 
little when it is desired to check the fire in moderate weather. 
This depends on the draft. 

For Burning Soft Coal.- — Some types of boilers are made to 
burn soft coal with economy, with least work. Some types are 
made specially to burn the meaner grades of soft coal. Firing 
to prevent smoke is a source of economy and these ways of run- 
ning should be followed — specially with large sectional boilers. 

There are two types of soft coal, viz. : The free-burning coal, 
which breaks apart when burning, allowing the gases to freely 
escape; and the fusing-coking coal, which, when burning, first 
fuses into a solid burning mass with a hard crust over the top, 
slowly coking as it burns. The latter kind is most valuable for 
house-heating boilers because the gases are more thoroughly 
consumed. The fusing-coking coal is worth about 20 per cent, 
more for this purpose than the free-burning coal. 

The gases should be allowed to pass off from the coal slowly. 
Leave air inlet on the feed door open if draft permits. If possible, 
use uniform sizes of coal. Avoid using coal having too much 
dust — the ''run-of-the-mine'' may be lower in price but its heat- 
making value is also low. 

For the purpose of slow burning of soft coal, it is well in feed- 
ing at night to let the fire burn up freely so that the coals are 
very live with heat. Then fill in enough coal to last all night — 
leaving some of the live coals uncovered if possible. With large 
sectional boilers this exposure should be at the rear of the fire so 
that the flame will pass over the live coals. Thus the gases 
coming off from the fresh coal are burned and a larger amount 
of the full heat-producing value of soft coal is made use of and 
with less smoke. 

After a boiler is so fed, the dampers (unless an automatic 
regulator is used) should be left about as follows : 

Ash-pit draft damper open a little or closed, as draft may 
require. 



76 MECHANICS OF THE HOUSEHOLD 

Cold-air check damper open about one-eighth to one-third 
distance of the opening. 

Smoke-pipe damper about one-half closed. 

A little experiment with the draft will usually tell the operator 
the best way of leaving these dampers. 

It will be found in the morning that the entire charge of coal 
is well burned or partly coked. 

The coked fuel, or that which sticks together in a mass, should 
be broken up by the poker and more added generally as by rules 
given in other sections. 

It must always be remembered that the soft coals mined in 
different parts of the country have widely varying heat-mak- 
ing capacities. To obtain satisfactory results brands must be 
selected which have an established reputation for excelling re- 
sults in small boilers. 

For Burning Coke.^ — It is best to keep the pot full of fuel — 
keeping a large body of coke under a low fire rather than a little 
fuel under a strong fire. 

It must be remembered that coke makes a very ^^hot fire^^ 
because the coke is free-burning. Care should be taken not to 
leave drafts on too long in boilers not having regulators. 

Coke burns best for house-heating purposes with less draft 
than is required for coal, therefore to keep a low fire the ash-pit 
draft damper should be kept closed, and the smoke-pipe damper 
almost entirely closed. The regulator (when used) can -be set to 
keep the dampers about as here advised. Coke is practically 
smokeless and its quick-burning character makes a cut-off damper 
in the smoke pipe (which will stay fixed as it may be set) quite 
necessary. 

It is well to keep a layer of ashes on the grates and when shak- 
ing stop before red-hot coals come through the grate. The coke 
then burns more slowly, which increases its effectiveness. 

With some drafts it may be well to ^^bank the fire^^ at night 
with coke — pea coal size. This is a matter of experiment, and 
depends on the character of the chimney draft. 

Fire should be tended regularly — two times a day, or four at 
the outside. 

With an extra strong draft, at night the fuel should be packed 
down by tamping with the back of a shovel. 



MANAGEMENT OF HEATING PLANTS 77 

With ordinary condition of draft, crushed coke, small egg size, 
should be used. 

Other Rules for Water Boilers — To Fill System, — Open the 
feed-cock when the heater is connected with a city or town water 
supply; if not, fill by funnel at the expansion tank. Fill until the 
gage-glass on the expansion tank shows about half full of water. 
In filling the system see that all air cocks on the radiators are 
closed. Then beginning with the lower floor, open the air cocks 
on each radiator, one at a time, until each radiator is filled ; then 
close the air cock and take the next radiators on upper floors until 
all are filled, after which let the water run until it shows in the 
gage-glass of the water tank. After the water is heated and in 
circulation, vent the radiators by opening the air valves as before. 
Then again allow the water to run into the system until it rises 
to the proper level in the expansion tank gage-glass. 

Always keep the apparatus full of water unless the building be 
vacated during the winter months, when the water should be 
drawn off to prevent freezing. Never draw water off with fire 
in the heater. 

To draw off water, open the draw-off cock at the lowest point 
in the system, and then open air cocks on all radiators as fast 
as the water lowers beginning with the highest radiator. 

Air-vent Valves on Radiators. — In order to secure the full 
benefit of the heating surface of a hot-water radiator, the inside 
of the section must be free of air. When a radiator is ^'air- 
bound/' it means that parts of the sections are filled with air 
in pockets which remain until the air is allowed, to pass off 
through the vent valve. 

Air will gather from time to time at the highest points inside 
the radiators, especially in those placed in the upper stories of the 
building. These air accumulations inside cut down the working 
power of a radiator exactly in proportion as they rob the inside 
of the casting of proper contact with heated water. Air pockets 
not only reduce effective heating surface, but they also prevent 
the circulation of hot water. 

Therefore, it is well once in a while to take the little key pro- 
vided by the heating contractor and open the air valves on radia- 
tors to allow the air (if any) to escape. When a radiator does 
not work as well as usual, open the air valves until the water 



78 MECHANICS OF THE HOUSEHOLD 

flows, which indicates that the air has been fully released. Then 
close the valve. 

Valves on Cellar Mains. — If cut-off valves have been placed 
on the main and return pipes in the cellar, see that the valves 
on one line of main and return pipes (at least) are open when the 
boiler is under operation. Be sure that the system is open to 
circulate water through the supply and return pipes before build- 
ing a fire in the boiler. 

End of the Season. — At the close of the heating season clean 
all the fire and flue surfaces of the boiler. Let the water remain 
in the system during the summer months. No bad results will 
follow if the system is not refilled more often than once in 2 or 3 
years. But, generally, it is thought that best results are secured 
by emptying the system once a year (after fire is out) and refilling 
with fresh water. 

It is a very good idea to take down the smoke pipe in the spring, 
thoroughly clean and put it back in place. Leave all doors open 
on the boiler in the summer time. 

Other Rules for Steam Boilers — To Fill Boiler, — Open the 
feed-cock when the heater is connected with city or town water 
supply; if not, fill through the funnel. Let the water run until 
the gage-glass shows about half full of water. 

In the first filling, after the water has boiled, get up a pressure 
of at least 10 pounds, draw the fire and blow off the boiler under 
pressure through draw-off cock to remove oil and sediment, 
after which refill with fresh water to the water line. This is best 
done usually by the steam-fitter. 

The damper regulator will control the pressure of steam, clos- 
ing the damper when the pressure is raised beyond the desired 
point and opening the damper when the pressure falls below that 
point. By removing the weight on the lever, different degrees 
of pressure can be kept up. The regulator should be allowed to 
control the drafts without interference. 

Examine the water glass often to see that the water line is at 
the proper height. If lower than normal open the supply pipe 
until the water runs in and stands at the proper level. It is best 
when no water stands in the glass, nor shows at the bottom of 
the try-cock, to quickly dump the grate and do not put water into 
the boiler again until it is cooled off. 



MANAGEMENT OF HEATING PLANTS 79 

If there is one or more shut-off valves on the main or return 
pipes, before starting a fire see that one Kne of piping at least 
(main and return) is open to circulate the steam. 

To Control Radiators. — When it is desired to shut off steam 
from any radiator (if the regular radiator valves are used), close 
the valve tightj and when it is turned on see that the valve is wide 
open, A valve partly turned off will cause the radiator to fill 
with water. This rule applies only to one-pipe heating systems. 

The Air Valves. — If little keyed air valves (sometimes called 
'^ pet-cocks' are used, follow generally the same directions as 
outlined for hot-water radiators on ^page 49- — only, of course, in 
releasing the air from the radiator open the valve with the key 
provided and close it just as soon as the steam unmixed with air 
comes through the nose of the valve. 

If ^^ automatic '^ air valves are used they must be carefully 
adjusted by the steam-fitter and then left to operate without 
undue interference. 

End of the Season. — At the close of the heating season fill the 
steam boiler with water to the safety valve and let it thus stand 
through the summer. 

Also thoroughly clean all the fire and flue surfaces of the boiler 
and at the opening of the next season withdraw the water and 
refill with fresh water to the water line, starting the boiler as 
before. 

It is advisable to have a competent steam-fitter blow off the 
boiler under pressure and thus give the inside a thorough cleaning 
when the boiler is first set up and ready for fire. 

A low-pressure boiler, using good water, rarely needs blowing 
off after it is once cleaned at time of setting up. 

THE RIGHT CHIMNEY FLUE 

The area of the flue should never be less than 8 inches in diame- 
ter if round, or 8 by 8 inches if square — unless for a very small 
heating boiler or tank heater. Nine or 10 inches round, or 8 by 
12 rectangular is a good average size. The flue should generally 
have a little more area than that of the connecting smoke pipes. 

Draft force depends very much on the height of the flue. 

The chimney top should run above the highest part of the roof 



80 MECHANICS OF THE HOUSEHOLD 

and should be so located with reference to any higher buildings 
nearby that the prevailing wind currents will not form eddies 
which will force the air downward in the shaft. Often a shifting 
cowl which will always turn the outlet away from the source of 
adverse currents will promote better draft. 

The flue should run as nearly straight up from the base to the 
top outlet as possible. It should have no other openings into it 
but the boiler smoke pipe. Sharp bends and offsets in the flue 
will often reduce the area and choke the draft. The flue must be 
free of any feature which prevents a free area for the passage of 
smoke. The outlet must not be capped with any device which 
makes the area of the outlet less than the area of the flue. 

The best form of flue is a round tile — in such there is less fric- 
tion than in the square form and the spiral ascent of the draft 
moves in the easiest and most natural manner. 

If the flue is made of brick only, the stack should be at least 
two 4-inch courses in thickness. 

If there is a soot pocket in the flue below the smoke-pipe open- 
ing, the clean-out door should always be closed. If this soot 
pocket has other openings in it — from fireplaces or other connec- 
tions — such arrangements are very liable to check the draft and 
prevent best action in the boiler. 

The smoke pipe should not extend into the flue beyond the 
inside surface of the flue, otherwise the end of the pipe cuts down 
the area of the flue and injures its drawing capacity. 

The inside of a flue should be smooth (pointed or plastered). 
When the courses are laid with the mortar bulging out from the 
joints the friction within the flue is very much increased. Often 
a troublesome flue is corrected by lowering some sharp-edged 
weight by a rope which should be worked against the sides of the 
flue until the clogging is scraped off. 

A new chimney when ^ ^ green ^' will not have a good drawing 
capacity. Short use dries out the mortar and better results 
follow. 

"Smokey" Chimney s.^ — The failure of draft in flues may be 
due to a variety of causes, one of which is illustrated in Fig. 576. 
The short chimney on the left side of the roof shows the course 
of the wind as it passes over the ridge of the roof and why the 
draft in such a chimney is retarded whenever this condition exists. 



MANAGEMENT OF HEATING PLANTS 



81 



The force of the wind, as it comes into contact with the roof, 
causes a compression of the air on the windward side and a rarifi- 
cation on the lee side. This inequaUty of pressure causes a 
downward sweep of the wind as indicated by the arrows. The 
effect on the low chimney is to retard the draft and sometimes 
the pressure is great enough to reverse the action of the flue and 






M3 




Fig. 576. — Effect of the wind in causing down draft in low chimneys. 

force the smoke into the house. The only remedy for such a 
condition is an extension of the chimney that will raise its top 
above the ridge. 

The same effect is often produced by a neighboring build- 
ing or a border of trees that are higher than the chimney and 
dense enough to effect the wind pressure. 



CHAPTER VI 
PLUMBING 

The term plumbing is usually understood to cover all piping 
and fixtures that carry water into the house and remove the waste 
material in the form of sewage. It does not include the pipes of 
the heating system. Although the work of installing heating 
plants is frequently done by plumbers, pipe fitting and plumbing 
are two distinct trades. 

In the process of building a house the rough plumbing is put 
into place as soon as the structure is enclosed and the rough 
floors are laid. The rough plumbing includes the soil pipe, into 
which the waste pipes from the various fixtures empty, and those 
pipes which must occupy a position inside the partition walls and 
beneath the floors. 

The connections here described are for a city dwelling and 
^PPly to the custom of local conditions. The same system 
might be used for a country residence except in regard to the 
water supply and method of sewage disposal. Plants of this 
type are discussed in the chapter on septic tanks. 

Fig. 58 shows a cross-section of the street, exposing the sewer 
aS, the water main W, and the connections with the house. The 
side of the house has been removed to permit a view of the water 
and sewer pipes, connecting with the bathroom, kitchen, laundry 
and other basement fixtures. 

The lateral sewer or house drain, which connects the house 
with the street sewer S, is provided with a trap G, located, in this 
case, just outside the basement wall. The house drain is made 
of vitrified tile, laid so as to grade into the street sewer with the 
greatest possible pitch. The sections are laid as true as condi- 
tions will permit and the joints are all carefully filled with cement 
mortar to prevent leakage. The object of the trap G is to prevent 
sewer gas from entering the house from the main sewer. The 
trap prevents the gas from passing because the water in the bend 

82 



PLUMBING 



83 



of the trap forms a water seal, beyond which the polluted air 
from the sewer cannot travel. 




Next inside the trap is the vent pipe E, that extends to the 
surface of the ground. In this case it is just outside the base- 



84 



MECHANICS OF THE HOUSEHOLD 



ment wall. The top is covered with a metal cap. Another 
arrangement often made to accomplish the same purpose is 
shown in Figs. 61 and 62, where a piece of soil pipe in the form of 
a bend is made to take the place of the cap. Inside the basement 
and extending up through the partition walls to the roof is the 
waste stack or soil pipe A, This pipe as is explained in detail 
later, is made of cast iron and is put together with calked lead 
joints. The top of the stack at the point where it passes through 
the roof is shown in Fig. 59. In extending through the roof the 
pipe A must make a water-tight joint to prevent water from 
leaking through. This is accomplished by means of the metal 

plate D, which is set under the 
B ^ shingles and the piece C, that is 

soldered to Z>, The joint between 
C and A is best made with lead 
the same as the other joints of the 
stack. In the ca^e of very high 





Fig. 59. — Detail of soil pipe 
connection. 



Fig. 60. — Cross-section of cellar-drain. 



stacks, the bottom should be supported by a pier or iron pipe 
rest. Besides being supported at the base the stack should be 
secured to the side walls or floor beams at each floor. This is 
to keep the pipe from moving out of place and the consequent 
opening of joints. 

All of the waste pipes from the bathroom, kitchen and base- 
ment drain into the waste stack. The cellar drain for draining 
the basement is shown at T in Fig. 58. It also appears in detail 
in Fig. 60. The plate 5, in the latter figure, is set flush to the 
surface of a depression in the floor that serves as a collecting 
point for water. The floor is constructed to drain toward this 
point. The plate is perforated to let the water through and is 
generally hinged so that in case of stoppage the cover may be 
raised. The bell-shaped piece under the cover surrounds the 
piece C, to form a water seal when the level of the water is at A. 



PLUMBING 



85 



In addition to this water seal there is generally a trap between 
the drain and the sewer as shown in the drawing. 

The method of connecting the bathroom waste pipes with the 
stack is shown in Fig. 99 and will be described later. All of the 
sewage of the house is emptied into the stack by the most direct 
route, and from the stack it is conducted as directly as possible 
into the sewer. From the drawing it will be seen that all open- 
ings to the sewer are sealed in two separate places, once at the 
outlet to prevent the air from the street sewer entering the house 
drain G, and again at each opening to prevent escape of the sewer 
gas from the drain into the house. 




Floor 



Trap 

Fig. 61. Fig. 62. 

Fig. 61. — House drain with outside vent, and running trap placed inside the 
basement wall. 

Fig. 62. — House drain with outside vent, and running trap placed outside 
the basement wall. 



The openings at E and A at each end of the stack permit a 
constant circulation of air for ventilation. The length of the 
stack and its location causes it to act as a chimney and the 
draught produced takes the air in at E, and discharges it at the 
top. In large houses there is sometimes added a vent stack to 
produce further ventilation, but in the average dwelling the 
arrangement here shown covers the common practice. 

In Figs. 61 and 62 are shown in detail two methods of arranging 
the sewer connections in the basement to permit of the removal 
of obstructions in case the pipes at any time become stopped. 
The trap, vent, etc., are easily recognized. With the arrangement 
as shown iit Fig. 62, the clean-out is so placed as to give access 
to the inside of the pipe. Should an accumulation or obstruction 
of any kind become lodged in the pipe, the stop in the clean-out 



86 MECHANICS OF THE HOUSEHOLD 

is removed and a flexible metal rod is used to remove the stop- 
page. The trap outside the wall has an opening through which 
the obstruction may be reached in case it cannot be removed 
from the first clean-out. The disadvantage in using the out- 
side trap, as here shown, is that it can be reached only by 
excavation. 

Fig. 61 shows another common method of installation. Here 
the trap is placed inside the basement wall. This gives an 
easier means of opening the trap than Fig. 62 affords and 
accomplishes the same purpose. The connections with the 
stack are the same as in Fig. 62. Obstructions in the sewer pipe 
are most likely to become lodged in the trap and for this reason 
the trap should occupy a position that is reasonably easy of 
access. 

The outside trap as described above is quite generally installed 
in buildings of all kinds, but its use is by no means universal. In 
some communities it is not used at all, and many plumbers 
consider it only an added means of causing stoppage and an 
extra expense to install. 

The object of the outside trap is to keep the air of the street 
sewer from entering the house drain. It is at once inferred that 
the air of the street sewer is more dangerous than that of the 
house drain. The street sewers, however, are ventilated at each 
street corner and at each manhole. There cannot then be much 
difference in the air of the two places. The traps on the fixtures 
that prevent sewer gas from entering the house would be just 
as efficient if the outside trap did not exist. 

While the methods shown in Figs. 61 and 62 are considered good 
practice, there is considerable objection to the vent being placed 
near the dwelling, because of the sewer gas that is forced out, 
whenever a sudden discharge of water goes into the drain. Each 
time a closet is flushed, a large volume of water enters the stack 
and completely fills the pipe. When this occurs, the descending 
water forces out the air of the pipe ahead of it, and a gush of 
offensive air filled with sewer gases is forced out of the vent. 
It is evident that such a vent, located near an open window or 
where it will reach the nostrils of the inhabitants is a thing 
not greatly to be desired. 

Outside traps when placed near the surface sometimes freeze. 



PLUMBING 



87 



The circulation of air through the vent is occasionally sufficient in 
cold weather to freeze the water and stop the trap. 

Water Supply. — ^The water supply taken from the street main 
is conducted to the house by the pipe shown in Fig. 58, at C. 




^^" 



^^ 



Fig. 63. — Corporation cock with lead connecting pipe. 

This pipe is generally of lead as piping of that metal is the most 
durable for underground work. Iron used under the same con- 
ditions will last only a few years. The connection is made with 
the water main by use of a corporation cock. 
This is a special style of cock that is shown 
in Fig. 63. In the figure the cock is connected 
with a short piece of lead pipe that is used for 
making connection with the service pipe in the 
house. 

Located at the left of C, in Fig. 58, is the 
curb-cockj used for shutting off the water from 
the city lot. The curb-cock, being under- 
ground, is reached through an iron tube by 
means of a wrench attached to a long iron 
rod. The curb-cock has a protective covering 
in the form of an iron pipe. The lower end of 
the pipe screws into the body of the cock. 
The top end comes just above the grade line 
of the curb and is covered with an iron screw- 
cap. The curb-cock is shown in detail in Fig. 
64. The pipe B is fastened to the valve at D 
and A is the screw-cap. In opening and clos- 
ing the wrench fits over the part C of the valve. 

On entering the building ther supply pipe should be provided 
with a stop and waste-cock for shutting off the water from the 
house and draining the pipes that compose the system of circuhi- 
tion. At F, in Fig. 58, is indicated a stop and waste-cock with 







Fig. 64.— Curb 
cock as it appears 
attached to the ser- 
vice pipe. 



88 



MECHANICS OF THE HOUSEHOLD 



the waste pipe B connected with the sewer. This cock is shown 
in detail in Figs. 65 and 66. The cock is so made that when 
closed there is a small opening at A, that allows the water from 
the system to escape through the waste pipe. 

From the water supply, the cold-water pipes may be traced in 
the drawing directly to each of the fixtures of the house. The 
hot-water pipe leaves the range boiler at the top and connects 
with each fixture using hot water, thus making the circuit com- 
plete. Details of the piping which provides hot water is de- 
scribed under range boiler, page 116. 




Fig 65.— Stop and drain 
cock with lever handle. 



Fig. 66. — Stop and drain 
cock with T handle. 



WATER COCKS 

The development of modern plumbing has brought about the 
use of a great number of household mechanical appliances, that 
have received trade names little understood by the average 
person. The lack of distinguishing terms, or language in which 
to describe plumbing fixtures, often leads to embarrassment, 
when such articles are to be described to workmen. Common 
household valves and cocks are so classified by the trade, that 
mistakes are often made in their designation, because of a limited 
knowledge of the use of the various articles. A little considera- 
tion of the different classes of fixtures will make it possible to 
state to a tradesman the exact article in question. 

The term valve is intended to define an appliance that is used 
to permit, or prevent, the passage of a liquid through the open- 
ing or port which it guards. The term is so general in its appli- 
cation that there are hundreds of different kinds of valves. 
Even for a single purpose there are many styles of a given kind. 



PLUMBING 



89 



A cock was originally a rotary valve or spigot used for draw- 
ing water. Today there are many kinds of cocks that are not 
rotary in their movement. 

It would be impossible in this work to describe in detail all 
of the kinds of cocks and valves used in household plumbing. 
It will, therefore, be the aim 
to confine attention to one 
article of a type and to choose 
such examples as are in general 
use and that are good repre- 
sentatives of their classes. 

Bibb -cocks. — ^On the 
kitchen sink, the water fau- 
cets, such as those shown in 
Fig. 66a, are termed bibb- 
cocks by the plumber. If the 
nozzle is plain, it is a "plain 
bibb. If the nozzle is threaded 
so that a hose connection 

may be attached as in Fig. 67, it is a hose bibb. Bibb-cocks are 
found in three general styles: compression bibbs, ground-key 
bibbs, and Fuller bibbs. The compression bibb takes its name 
from the method of closing the valve. Fig. 68 gives an ex- 
ample of its mechanical construction. This is a plain solder bibb 




Fig. 66a.- 



-Kitchen sink with Fuller 
bibb-cocks. 




Fig. 67. — Compres- 
sion hose bibb. 



Fig. 68. — Compres- 
sion flange bibb. 



Fig. 69. — Cross-section 
of plain compression bibb- 
cock for a solder joint. 



because the shank A is to be attached by a solder joint. If the 
part A contained a thread to make a screw joint, such as Fig. 
67, it would be a plain, compression, screw bibb. Fig. 68 is 
another style of compression bibb-cock, largely used on sinks; 
this cock, being finished with a flange, is a compression flange bibb. 



90 



MECHANICS OF THE HOUSEHOLD 



Fig. 69 shows quite clearly the mechanical arrangement of 
the compression cock. When the handle is turned the nut C lifts 
the valve from its seat 5, allowing the water to escape. The 
piece D is generally made of composition rubber that may be 
bought at the dealers for a trifling amount but it may be re- 
placed temporarily with a piece of leather. The part E is 
packing, to keep the water from leaking out around the stem. 
The packing may be obtained from the dealer especially for the 
purpose or it may be made of a disc of sheet rubber. In fact, 
anything that can be put into the space will answer the purpose 
temporarily. The valve is closed by compression, hence the 
name compression cock. All cocks made to open and close in the 
same manner are compression cocks. 




Fig. 70. — Cross-sec- 
tion of plain self-closing 
bibb-cock for lead pipe. 



Fig. 71. — Cross-sec- 
tion of lever handle, 
plain bibb. 



Fig. 72. — Cross-section of 
plain Fuller bibb for lead 
pipe. 



Self-closing Bibbs. — In Fig. 70 is one example of the many 
styles of self-closing bibb-cocks. When the handle of this cock 
is turned, the steep- pitched screw A opens the valve and at the 
same time compresses the spiral spring 5, when the handle is 
released, the valve is pressed back on its seat by the spring. 
Self-closing cocks are used to prevent the waste of water at 
drinking fountains, wash basins and other places where the 
water is apt to be left running through carelessness. 

Lever-handle Bibbs. — Fig. 71 is an example of the lever- 
handle, ground-key bibb-cock. The key is the piece A, which is 
tapered and forms a ground joint with the part B. The cock 
takes its name from the form of the handle. The term ground- 
key means that the key has been ground into place with emery 
dust. This cock iskeptfromleakingby adjustment of the screw C 



PLUMBING 91 

Fuller Cocks. — These cocks take their name from their 
inventor. They are made to suit every condition for which 
water cocks are used. Their universal use attests to their 
utihty and excellence in service. Fig. 72 shows the principle 
on which all Fuller cocks work. The varying conditions under 
which the cocks are used require a great many forms, but the 
working principle is the same in all. In these cocks, the valve 
is a rubber plug or ball that is drawn into the opening by an 
eccentric piece attached to the handle. The piece D in the draw- 
ing is the rubber plug that is drawn against the opening by the 
, crank B, which is worked by the lever handle A. This cock may 
be repaired, in case it leaks, by unscrewing it at the joint nearest 
the plug. A wrench and a pair of pliers are all the tools required. 
The pieces D must be obtained from the dealer. The part J is 

Ball Stem with Ball 



Fig. 73. — Repairs for Fuller cocks. 

the packing that keeps the water from leaking out around the 
stem. The screw- cap H forces a collar / down on the packing 
to keep it water-tight. 

The parts for the Fuller cock that may be obtained for repair 
are shown in detail on Fig. 73. The ball, which appears in Fig. 
73 at Dj is the part that receives the greatest- amount of wear. 
If the cock at any time fails to stop the flow of water, a new ball 
may be put in place by the aid of a wrench and a pair of pliers. 
The water being first shut off from the system, the cock is un- 
screwed and the cap E removed with a pair of pliers. The worn 
ball is then removed and a new one substituted. 

Wash-tray Bibbs. — A special style of cock is made for hiundry 
wash trays in both the Fuller and compression types. Of these 
the Fuller type is the most convenient as the handle is placed on 
the side and but one movement is required to open the cock. 
This style of cock is used on the wash trays shown in Fig. 83. 



92 



MECHANICS OF THE HOUSEHOLD 



Basin Cocks. — Water cocks for wash basins are made in two 
general types — the compression and the Fuller types of cocks. 

Their mechanism is much the same as 
for other similar styles adapted to the 
use for basins. The self-closing cocks 
used so largely on wash basins are com- 
pression cocks. Fig. 74 is an example 
of Fuller basin cock in general use. 
Compression cocks for the same purpose 
are shown on the wash basin in Fig. 90. 
Pantry Cocks.^ — ^In general form, 
pantry cocks are the same as those used 
for basins except that the outlet is 
elongated. 

Sill Cocks. — As a means of attaching 
garden hose or lawn sprinklers, sill cocks 
are placed on the side of the building 
at any place convenient for their use. 
Fig. 75 illustrates the method of attach- 
ing the cock to the water supply. Fig. 76 shows in cross-section 
its mechanical arrangement. The part A is screwed into the 
water supply, and B furnishes the hose attachment. The valve 




Fig. 74. — Fuller basin 
cock. 




VZ2^2^^. 



Fig. 75. — Sill cock in place at- 
tached to the water pipe. 




Fig. 76. — Cross section 
of sill cock. 



is operated the same as any other compression valve. In Fig. 
75 the cock is shown at A with a garden hose attached. The 



PLUMBING 



93 



pipe to which A is attached passes into the basement and con- 
nects to the water supply. The stop-cock B is used to shut off 
the water. When the stop-cock B is closed, A should be opened, 
so that the pipe will drain. If this is neglected during freezing 
weather, the pipe is apt to freeze and burst. 

Valves. — The distinction between a cock and a valve is not at 
all definite. Custom has determined that in certain places a 
cock shall stop the flow of a liquid but in another place, perhaps 
of a similar nature, a valve shall accomplish the same purpose. 
The chief distinction between a cock and a valve is that of its 
external form. 

In Figs. 77, 78 and 79 are three examples of valves that are 
very generally used on pipes carrying any kind of fluid. The 




( H-^ ) 



Fig. 77. — Cross-sec- 
tion of globe valve with 
detachable valve disc. 





Fig. 78. — Cross-section 
of angle globe valve. 



L -B 



Fig. 79. — Cross-section 
of gate valve. 



valves are shown in cross-section to display the arrangement 
of the mechanism. 

Fig. 77 is an example of the common globe-valve. The name was 
originally intended to define a valve the body of which was in 
the form of a globe. The hand-wheel H, attached to the screw- 
stem iS, raises the valve A when desired. The valve makes close 
contact with the seat C, by means of a composition rubber disc 
B. The disc B may be renewed when worn out as in the case of 
the radiator valve already described. 



94 MECHANICS OF THE HOUSEHOLD 

Fig. 78 represents an angle globe-valve. In general construction 
it is quite similar to Figs. 14 and 15, but the valve V in this case 
is a cone-shaped piece of brass, which makes a seat in a depression 
provided for it. The valve V and the seat are formed as desired 
and then ground into contact with emery dust or other abrasive 
material, to assure a perfectly tight joint. When this valve 
becomes worn and begins to leak, it maybe repaired by regrinding, 
but such work requires the services of a pipe-fitter. The tendency 
of modern practice is to use valves with the detachable discs, such 
as that of Fig. 77, because they are easily repaired. 

The valve shown in Fig. 79 is known as b. gate-valve. The 
upper part, including the screw and stem, is the same as the 
globe style but the valve proper is made in the form of two 
flat gates A~A, When the valve is closed, as it appears in the 
drawing, the gates are forced against the seats by the cone- 
shaped piece Bj which acts as a wedge, to tightly close the opening. 
When the hand-wheel is turned to open the valve, the gates are 
raised and are taken entirely out of the path of the flowing 
liquid. Gate-valves are used in places where it is desired to 
obstruct the flow as little as possible. They are somewhat more 
expensive than globe-valves but are considered worth the 
extra expense in service. 

Kitchen and Laundry Fixtures. — The development in modern 
plumbing has wrought many changes in the styles of household 
fixtures but none has been so great as that in the kitchen sink. 
The old style, insanitary, wooden sink has been almost entirely 
replaced by those made of pressed steel or enameled iron. They 
are made in every desired size and to suit all purposes. They 
may be plain or galvanized as occasion may require, or the enam- 
eled sink is obtainable at a very slight addition in price. The 
enameled sink has reached a degree of perfection where its dura- 
bility is unquestioned, and as a consequence kitchen furniture 
is vastly improved at but little advance in cost. 

A modern kitchen in which gas is used as fuel is shown in Fig. 
80. Simplicity and neatness of arrangement are the noticeable 
features. This kitchen is intended to suit the average-sized 
dwelling and contains all necessary plumbing, cooking and heat- 
ing apparatus. The hot-water boiler is here shown attached to 
an instantaneous heater. The common kitchen sink is supple- 



PLUMBING 



95 



merited with a slop sink and covered with a drain board. This 
simple kitchen may be elaborated to any extent. Fig. 81 shows 




Fig. 80.— Model kitchen. 







1 




B 


HH " '^''IHH^K 


r r 


' 




"l 





Fig. 81. — White enamel kitchen sink. 



a kitchen sink of white enamel with two enameled drain boards. 
The drain boards are sometimes covered with perforated rubber 
mats. 



96 



MECHANICS OF THE HOUSEHOLD 



In Fig. 82 is shown an example of the modern basement laun- 
dry. The wash-boiler heater is shown on the left. An auto- 




FiG. 82. — Model laundry. 













IMl^iii^^ 


rr 


m 




-^ I,, k M^H^O 


^tJ_i_ 








1 A ^ ■ - - -' 


i 




^^^^p^^H 










■ 



Fig. 83. — Enamel wash trays in a basement laundry. 



matic instantaneous water heater is on the right. The station- 
ary tubs or wash trays occupy the center of the picture. In detail 



PLUMBING 



97 



these wash trays appear in Fig. 83. These are enamel-covered 
ware and are provided with the wash-tray bibb-cocks described 
above. This type of plumbing represents the most modern of 
sanitary arrangements. 

THE BATHROOM 

With the present-day improvements in plumbing, and the 
perfection in the manufacture of porcelain and enameled iron, 
the bathrooms of houses of moderate cost have become places of 




Fig. 84. — Model bath room for the average dwelling. 

cleanliness, attractive, relatively free from offending odors and 
supplied with all necessary sanitary fixtures. 

Enameled iron has reached a state of perfection where it rivals 
porcelain in beauty. The forms of the various bathroom pieces 
have been modeled for convenience in use and grace of form, at 
the same time the strife of the designer has been to produce 
articles that not only look well but are convenient and easily 
kept clean. 

Bathrooms need not be expensive in order to be convenient 
attractive and useful. The bathroom shown in Fig. 84 is such 
as is installed in dwellings of moderate price. It possesses every 
feature necessary to usefulness and comfort. In this room the 

7 



98 



MECHANICS OF THE HOUSEHOLD 



furnishings are all of enameled iron. The floor is covered with 
linoleum and the wainscoting with enamel paint. 

Bath Tubs.- — Bath tubs are made in sizes that vary in length 
from 43-^ to 6 feet. They are constructed in a variety of forms 
and of materials to suit all conditions of service. For domestic 
use they are very generally made of enameled iron. This form 
of construction produces serviceable and handsome furnishings 
for the bathrooms of the modest house as well as for the 
sumptuous bath of the most pretentious residence. An elabora- 
tion of Fig. 84 might include the Sitz bath shown in Fig. 85 and 

the fittings may be chosen 
from a great variety of forms. 
The recent styles of enameled 
tubs are, in design, much 
handsomer than those with 
the roll rim and in form such 
as permits a clean room with 
the minimum of labor. They 
are also provided with more 
convenient water and drain- 
age fixtures. 

The tub of Fig. 86 sets flat 
on the floor and makes a close 
joint with the wall. It thus 
prevents the accumulation of 
dust that is difficult to remove. In addition the fixtures are ar- 
ranged in a more commodious manner and the general appearance 
is most pleasing. The arrangement of the fixtures in Fig. 87 gives 
still greater convenience and being arranged with a shower and 
protecting curtain, provides all of the conveniences of a luxuri- 
ous bath without greatly increased cost over the simple tub. 
The fixtures in this design are all in position of greatest con- 
venience and attached to pipes that are concealed in the wall. 
The fixtures usually provided with the tub are double Fuller 
or compression cocks for hot and cold water, the overflow and 
strainer, for the discharge of the water into the sewer in case the 
tub overflows, and a drain and bath plug. 

The double Fuller cock is shown in Fig. 88. It is made to open 




Fig. 85.— Sitz bath. 



PLUMBING 



99 




Fig. 86. — Enameled iron bath tub. 




Fig. 87. — Bath tub with shower. 



100 



MECHANICS OF THE HOUSEHOLD 



and close by the same sort of mechanism as is shown in Fig. 71, 
a description of which appears on page 90. 

The overflow is shown in detail in Fig. 89. The part A appears 
inside the tub. It is made water-tight around the edge C by a 




Fig. 88. — Double Fuller cock for bath tubs. 

rubber washer that is clamped tight to the surfaces by the nut 
JS. In case of leakage, the overflow may be removed for repair 
by unscrewing the union attached to the piece D and removing 
the nut B. 




Fig. 89. 



Fig. 89a. 



Fig. 89. — Overflow attachment for bath tubs, lavatories, etc. 
Fig. 89a. — Drain attachment for bath tubs, avatories, etc., showing lock- 
nut and union connection. 



The drain-pipe connection is shown in Fig. 89a. The plug D 
and the flange A show inside the tub. The flange is made 
water-tight by a rubber washer that the nut B clamps tight to 
the tub. The part C is a union which permits the tub to be 



PLUMBING 



101 



detached from the drain pipe. Repairs to this joint may be 
made as in the overflow. 




Fig. 90. — Old style marble finished 
lavatory. 




Fig. 91. — Types of lavatory plumbing 
not now used in good practice. 



Wash Stands and Lavatories. — Wash stands for bathrooms are 
obtainable in many forms, either plain or ornate, to suit every 
condition and style of architectural finish. 




'4^^^^^^^^^ 


IH*^ 


% ^ 




..-/ 




i 


r 




w^ 



Fig. 92. — Enameled iron wall 
wash basin. 



Fig. 93. — Enameled iron pedestal 
wash basin. 



They are made in marble, porcelain and cMianielod iron, the 
last being the most commonly used. They are made to suit the 
part of the room to be occupied, whether that is against a wall, 



102 



MECHANICS OF THE HOUSEHOLD 



a corner, or to stand on a pedestal on the floor. Those intended 
to fasten to the wall may be supported by brackets or suspended 
at the back from pieces secured in the wall. 

In Figs. 90 and 91 are shown samples of marble-finished wash 
basins. In former years basins of this type were very much in 
use, and until the introduction of the modern porcelain and en- 
ameled ware, it was the highest type of sanitary plumbing. The 
water cocks and traps are of the same style and grade as appear 
on the most modern examples of enameled ware of Figs. 92, 93 and 
94. The water cocks used in Fig. 90 are of the compression type. 

All of the others are of the Fuller 
type. The basin in Fig. 93 is pro- 
vided with extra shut-off cocks on 
the water pipe under the basin. They 
are added to the plumbing merely as 
a convenient means of shutting off 
the water for repair. The wash stand 
is usually provided with hot and cold 
water cocks, a waste pipe with its 
traps and overflow connections. 

Traps. — The waste pipes from the 
wash basin and bath tub are always 
provided with some form of trap, to 
prevent air from entering the room 
from the sewer, charged with offend- 
ing odors. Traps are made in many 
forms, but the purpose of all is to prevent the escape of sewer gas. 
The plain trap >S, shown in Fig. 95, is that used under the basin 
in Fig. 91. It makes a tight joint by means of the nut B and a 
rubber washer as in the case of other joints of the kind. The 
parts C and E are unions that permit the pipe or bowl to be 
removed without disturbing the remainder of the plumbing. 
From the form of the trap it will be seen that the U-shaped part 
below the dotted line F will always remain full of water and so 
prevents the escape of air from the sewer. In case the trap 
becomes stopped the obstruction will likely become lodged in 
this part of the pipe. To clean the trap the screw-plug D is 
taken out with a pair of pliers and the obstruction removed with a 
wire. 




Fig. 94. — Corner wash basin. 



PLUMBING 



103 



The traps used in Figs. 90 and 92 are the same in principle as 
Fig. 95 but are made to discharge into a pipe placed in the wall in- 
stead of under the floor. The trap in Fig. 94 is a form known 
as the bottle-trap that is sometimes used in the more expensive 
plumbing. 

Another style much used with lavatories is the Bower trap 
shown in Fig. 96. In this trap the water comes down the pipe 
B and pushing aside the hollow rubber ball A, enters the space 
surrounding it and is discharged at C. The ball, being light, is 




FIG. 98 



FIG.96 



F1G.95 

Fig. 95. — The S trap of nickel-plated brass tubing. 

Fig. 96. — The Bower non-siphoning trap. 

Fig. 97. — The drum type of non-siphoning trap. 

Fig. 98. — An S trap made of lead pipe. 



held against the end of the pipe by the water and acts as a stopper 
to prevent evaporation from taking place. Open traps, such as 
Fig. 95, if left standing for a long time, may lose sufficient water 
by evaporation to destroy the water seal and allow the sewer gas 
to escape. In the use of the Bower trap such occurrence is much 
less likely to take place. 

Fig. 97 is another trap much used on sinks; it is known under 
the trade name of the Clean Sweep trap. The part (' is nuich 
larger than the common trap and the water seal is less likely to 



104 



MECHANICS OF THE HOUSEHOLD 



be broken. The clean-out is larger and the interior is easy of 
access in case of stoppage. 

The simplest and most commonly used trap in cheap plumbing 
is that of Fig. 98. It is a lead pipe bent in the form of an aS. It 
is the same in shape as Fig. 95 and performs its work as well but 
does not have the means of detachment shown in the latter. 
Traps of many other forms are in use but all have the same 
function to perform and the mechanical make-up is much the 
same as those described. 

The plan of attachment of the various bathroom fixtures of the 
soil pipe must always depend on local conditions. The object 




DETAIL N 



==sl-^ 



DETAIL L 

Fig. 99, — A method of bath-room plumbing using the drum trap. 

is to conduct the waste water to the sewer in such a way as to 
give the least opportunity for stoppage and to prevent sewer gas 
from escaping into the house. To accomplish this purpose the 
pipes and traps are arranged according to a plan proposed by the 
architect, plumber or other person familiar with the principles of 
plumbing. Since these pipes are placed in the walls and under 
the floors, where they are not readily accessible, it is necessary 
that their arrangement be made with care and that the work- 
manship be such as to assure correct installation. 

In Fig. 99 is shown a common method of connecting bathroom 



PLUMBING 105 

fixtures with the sewer. The drawing shows a bathroom with 
the floor broken away to show the pipe connections with the bath 
tub, wash basin and closet. The overflow pipes and V and the 
drain pipes D and R from the wash basin and bath tub empty into 
a large lead drum-trap T, set under the floor. This trap takes its 
name from its shape. It is set in position as dictated by the condi- 
tions under which it is used. The nickeled plate P, screwed into 
the top of the trap, comes just above the bathroom floor. This 
plate is easily removed in case of stoppage. It is made air-tight 
by a rubber ring placed under the cover and which makes a joint 
with the top edge of the drum. 

It will be noticed that the waste pipes from the bath tub and 
wash basin enter the trap near the bottom and discharge at the 
opposite side near the top. The water will stand in the trap and 
pipes level with the bottom of the discharge pipe and thus form 
a seal that prevents the escape of sewer gas. This is a common 
form of non-siphoning trap. It is non-siphoning because it 
cannot lose its seal by reason of the siphoning effect of the water 
as it passes through the waste pipes on its way to the sewer. 
Another form of non-siphoning trap is the clean sweep trap shown 
in Fig. 97. Such traps as Figs. 95 and 98 are siphoning traps, 
sinae it is possible, in this form of trap, for the water to be so 
completely siphoned that not enough remains to form a seal. 
The small drawing, marked Detail L, is another method of con- 
necting the same arrangement of fixtures. The waste pipe enters 
the trap as before but discharges immediately opposite. The 
level of the water stands in the pipes as indicated by the dotted 
Ime. 

Back -venting.— To prevent the possibility of loss of seal by 
siphoning and the escape of sewer gas, traps are back-vented to 
the main stack or to a separate vent stack. The venting is 
accomplished by joining a pipe to the top of the trap or to some 
point in its immediate neighborhood, and connecting this with 
the main stack or the vent stack. The water in a trap so vented 
will be open to the air from both sides and consequently can never 
be subject to siphonic action. 

In the average-sized dwelUng where non-siphoning traps 
are used, back-venting is not necessary, but in large houses and 



106 



MECHANICS OF THE HOUSEHOLD 



in plumbing where siphon traps are used, vent pipes must be at- 
tached to the traps to assure a satisfactory system. 

Fig. 100 furnishes an example of back-venting, applied to the 
bathroom shown in Fig. 99. In the former figure the bath tub 
and wash basin are connected with the waste pipe by siphon 
traps. A siphon trap may lose its seal in two ways: by self- 
siphonage, or by aspiration caused by the discharge of the water 
from other fixtures. In the discharge of the siphon trap, such 
as B, in Fig. 100, the long leg of the siphon, formed by the dis- 
charge pipe, may carry away the water so completely that not 
enough remains in the trap to form a seal. Again, the discharge 
of the water from the bath tub through the waste pipe tends to 




Fig. 100. — An example of back-vented plumbing as applied to the bathroom. 



form a vacuum above it and in some cases the seal in B is de- 
stroyed by the water being drawn into the vertical pipe. The 
possibility of either of these occurrences is prevented by 
back-venting. 

In Fig. 100, a pipe from the main stack is connected with the 
bend of the trap at B and also to the waste pipe outside the trap 
at T. A vent is also taken from the drain C, at a point just 
below the trap in the closet seat. The object of all of the vents 
is to prevent the tendency of the formation of a vacuum from any 



PLUMBING 107 

cause that will carry away the water seal of the trap and allow 
sewer gas to enter the house. 

The closet seat also contains a trap which will be described 
later. It connects with soil pipe /S, leading to the sewer by a 
large lead pipe C, 

All of the pipes under the floor, leading to the soil pipe, should 
be of lead. The pipes above the floor are generally of iron or 
nickel-plated brass. All of the connections in the lead pipes are 
made with wiped joints; that is, the connections are made by 
wiping hot solder about the joint, in a manner peculiar to this 
kind of work, in such a way as to solder the pipes together. The 
joints made in this manner are perfectly and permanently tight. 
Lead pipes are used under such conditions, because lead is the 
least affected by corrosion of any of the metals that could be 
used for such work. 

Soil Pipe.- — The soil pipe, of which the waste stack or house 
drain is composed, is made of cast iron and comes from the factory 
covered with asphaltum paint. It may be obtained in two 
grades, the standard and extra heavy. The only difference is in 
the thickness of the pipe. The former is commonly used in the 
average dwelling. One end passes through the roof and the other 
end joins to the vitrified sewer tile under the basement floor. 
The joints* must be perfectly tight, because a leak in this pipe 
would allow sewer gas to escape into the house. One end of 
each section is enlarged sufficiently to receive the small end of 
the next section. The joints are made with soft lead. The 
pipes are set in place and a roll of oakum is packed into the bot- 
tom of the joint, after which molten lead is poured into the 
joint, filling it completely. The oakum is used only to keep the 
lead in the joint until it cools. After the lead has cooled it is 
packed solidly into the joint with a hammer and calking tool. 
The calking is necessary because the lead shrinks on cooling 
and makes a joint that is not tight. Well-calked joints of this 
kind are air-tight and permanent. Detail N (Fig. 99) shows the 
arrangement of the parts of the joint as indicated at A. The 
blackened portion represents the lead as it appears in the joint. 

Detail M (Fig 99) shows the methods of attaching the closet 
seat to the lead waste pipe C. The end of the load pipe is flanged 
at the level of the flooi", as shown at C in the detail drawing. 



108 



MECHANICS OF THE HOUSEHOLD 



The depression D, around the connection, is then filled with 
glazier's putty and the seat is forced down tightly in place and 
fastened with lag screws. 

The pipe C, from the closet, and that from the trap T, being of 
lead, a special joint is necessary in connecting them with the soil 
pipe, because a wiped joint cannot be made with cast iron^ To 
make such a connection the end of the lead pipe is ^^ wiped'' onto 
a brass thimble, heavy enough to allow it to be joined to the soil 
pipe by a calked lead joint. The brass thimble is then joined to 
the cast-iron pipe by a calked lead joint. 

Water Closets. — Water closets are made in a great number of 
styles to suit the architectural surroundings and the various 
conditions under which they are to be used. Many forms of 




Fig. 101. — The wash-out 
closet. 



Fig. 102.— The wash-down 
closet. 



water closets are manufactured to conform to special conditions, 
but those commonly used in the bathrooms of dwellings are of 
three general types. The mechanical construction of each is 
shown in the following drawings, Figs. 101, 102 and 103 showing 
respectively in cross-section the principle of operation of the 
washout closet, the washdown closet and the siphon-jet closet. 
Washout Closets. — ^This type of closet has in the past been 
used to a very great extent. It does not perform the work it has 
to do, so perfectly as the others, because the shallowness of the 
water in the bowl allows it to give off odors, and because it is 
difficult to keep clean. The action of the closet is as follows: 
When the closet is flushed the water enters the rim at A , and the 
greater portion of it is washed downward at B to dislodge the 
contents of the bowl. A lighter flush is sent through the openings 



PLUMBING 109 

in the side, which serves to wash the entire surface. The direc- 
tion of discharge is forward, where it dashes against the front 
of the bowl and then falls into the trap. The only force received 
to carry the water to the trap is from falling through the distance 
from the point where it strikes the front. The flushing action 
is obtained from the use of a large volume of water. As the 
discharged matter is dashed against the front of the bowl, the 
flushing action of the water is not suflftcient to remove all the 
stains; the result is an accumulation of filth. This part of the 
bowl is out of sight; hence, it is seldom kept clean. The name 
washout comes from the action of the water to wash out the con- 
tents of the bowl. 




Fig. 103. — The siphon-jet Fig. 104. — A poor design of 
closet. wash-down closet. 

Washdown Closets. — As shown in Fig. 102, the action of this 
closet is to wash the contents of the bowl directly down the soil 
pipe. The depth of the water at A is much greater than at the 
corresponding point in the washout closets; as a consequence 
fecal matter is almost submerged. The main objection to this 
closet is that it is noisy. Fig. 104 shows another form of wash- 
down closets. This closet is open to objection because of faulty 
design; the part A is difl^icult to keep clean because of its shape. 

Siphon-jet Closet. — What is considered by many to be the 
most satisfactory closet yet designed, is that of the siphon-jet 
type shown in Fig. 103. The flushing action of this closet is 
entirely different from that of the others described. The flush- 
ing water enters at A and fills the rim B. Part of the water 
washes the sides of the bowl, while the remainder flows through 
the jet C, and is discharged directly into the outlet. The ejected 
water enters the outlet Z>, which, as soon as it fills, acts a^ a 
siphon to draw the water into the soil pipe. This closet is most 



110 



MECHANICS OF THE HOUSEHOLD 



positive in its action, since the discharge is made by the siphon 
and also receives the additional momentum due to the water 
flowing through the jet. Its action is attended with but little 
noise. 

Flush Tanks.^ — The water closet depends for its action on one 
of two general types of flush tanks, the high and the low forms. 
The tank is automatically filled with water and when wanted, a 





Fig. 105. — Siphon-jet closet 
with the high flush tank. 



Fig. 106. — Form of closet not 
now used in good practice. 



large volume of water is suddenly discharged into the sewer, 
carrying with it the contents of the seat. The tank again fills 
and is ready for use when required. 

As illustrations of high flush tanks, those shown in Figs. 105 
and 106 furnish examples of a simple and efficient form. The 
details of the mechanism of this type of tank are shown in Fig. 
107. The pipe from the water supply is attached at G to the 
automatic valve F, which keeps the tank filled with water. The 
piece F of the valve is held against the opening by the pressure 
exerted through the float E, The float is a hollow copper ball. 



PLUMBING 



111 



As the ball is lifted it exerts a^ pressure in proportion to the 
amount it is submerged. When the water reaches the level 
A-A, the valve is tightly closed. As the water is discharged 
from the tank the ball follows the level of the water and opens 
the valve, allowing the water to enter and again fill the tank. 
The siphon is made of cast iron, and in the figure is shown cut 
through the center. The lower end fits loosely in the piece K, 
and makes a water-tight joint around its outer edge, by resting 
on a rubber ring C-C The right-hand side of the siphon is 
open at H, and when the tank is full, the level of the water is at 
A" A, which is almost at the top of the division plate. To dis- 
charge the tank, the chain L, attached to the lever B, is pulled 
down; this action raises the siphon from its seat. As soon as the 
siphon is lifted, the water rushes through the opening around 




Fig. 107. — Details of construction of a simple type of siphon flush tank. 

C-Cj into the pipe K] this causes a partial vacuum to form in 2), 
and the water is lifted over the division plate K, and flows out 
at D, forming the siphon. As soon as the siphonic action begins 
the siphon may be dropped back on the seat and the water will 
continue to discharge until the tank is empty. 

Low-down Flush Tank. — The low-down flush tank for water 
closets has met with so much favor that it has to a great extent 
displaced the high tank. The reason for this is because of its 
advantages over the other style. The low tank is more accessible, 
more easily kept clean, and better adapted to low ceilings. 
It is used successfully as a siphon tank, but other forms are in 
use with satisfactory results. 

Fig. 108 gives a perspective view of one style of this type of 
tank attached to a siphon-jet closet. Figs. 109 and 110 give the 



112 



MECHANICS OF THE HOUSEHOLD 



details of the construction of two forms of this type of tank, 
both of which have given efficient service. The drawing shows 
the tanks with the front broken away to give a view of the work- 
ing parts. The water enters the tank and is discharged at the 
points indicated. The float and supply valve works exactly as 
described in the high tank. The drawing in Fig. 109 shows 
the tank in the act of discharging. The discharge valve is raised 
as shown at E. When the water is completely discharged, the 
float occupies the position shown dotted. When the float reaches 
this dotted position, its weight pulls down the piece A. This 





Fig. 108.— Siphon- 
jet closet with low- 
down tank. 



Discharge 



Fig. 109. — Details of construction of low-down 
flush tank. 



releases the lever B, and the attached stopper E, which falls arid 
closes the discharge orifice. While the tank is filling with water, 
a stream flows through the small pipe Z>, to replenish the water 
in the closet that has been discharged in siphoning. When the 
tank is full of water, the pieces A and B occupy the positions 
shown dotted. To discharge the tank the trip is pushed down. 
This action raises the lever to the position 5, and with it the 
attached stopper E, The piece C falls and the opposite end A 
holds B suspended until the tank is completely discharged. 
The action of the tank shown in Fig. 110 is the same as the 
others except that of the discharge mechanism. In the drawing, 
the tank is full of water ready to be discharged when required, 



PLUMBING 



113 



A hollow rubber ball E serves as a stopper for the discharge 
pipe. The ball is kept in place, when the tank is filling, by the 
pressure of the water above it. The discharge is started by press- 
ing down the trip on the front of the tank. This raises the ball 
from its seat, and being lighter than water, it floats, thus leaving 
the discharge pipe open until the tank is empty, when the ball 
is again back on its seat. As the tank fills the pressure of the 
water above prevents the ball from again floating, until lifted 
from its seat. The supply valve and refilling pipe D is the same 
in action as in the other tank. 





Fig. 110. — Details of construction of the 
fioat-valve, low-down flush tank. 



Fig. 1 1 1 .—Method of 
using the plumber's friend, 
in removing obstructions. 



Opening Stopped Pipes.^ — It occasionally happens that pipes 
leading from the various toilet fixtures become stopped because of 
accumulations or by articles that accidentally pass the entrance. 
In case the pipe has a trap connection the stoppage is most likely 
to occur at that point. Usually the obstruction may be removed 
by detaching the screw-plug of the trap and removing the accu- 
mulation with a wire. 

Closet seats furnish an inviting receptacle for waste material 
of almost every kind. Stoppages are not uncommon and are 
generally found in the trap. One method of removing obstruc- 
tion is by use of the pluml)ers^ friend. This device is shown at 

8 



114 



MECHANICS OF THE HOUSEHOLD 



P-Rj in Fig. 111. It consists of a wooden handle P attached to 
a cup-shaped rubber piece R, 

The plumbers' friend is shown in the figure, placed to remove 
an obstruction S that is lodged in the trap. A sudden downward 
thrust causes the rubber cap R to entirely fill the closet outlet 
and the resulting pressure to the water is generally sufficient 
to force the obstruction through the trap to the soil pipe. 

The kitchen sink is another place that affords opportunity 
for accumulation that stops the waste pipe. Accumulation of 

grease in the trap is a common 
cause of trouble. . This may be 
remedied to some extent by the 
use of potash or caustic soda. 
When the pipe is stopped and 
the trouble cannot be reached 
from the trap, a common method 
of removing the stoppage is that 
suggested in Fig. 112. A piece 
of heavy rubber tubing is forced 
over the water tap and the other 
end tightly wedged into the drain 
pipe; the water is then turned 
on and generally the pressure is sufficient to force the accumu- 
lation down the pipe. 

Sewer Gas. — The prevalent fear of the deleterious effect of 
escaping sewer gas is one that has been magnified to an un- 
warrantable degree. Among bacteriologists it is very generally 
recognized that none of the dreaded diseases to which the human 
kind is susceptible are transmitted by gases. The one possible 
harmful effect recognized in sewer gas by scientists is that pro- 
duced by carbon monoxide. Sewer gas often contains, from es- 
caping illuminating gas, sufficient carbon monoxide to produce 
the poisoning effect characteristic of that gas but the possibility 
of danger is quite remote. The leakage of sewer gas is detected 
by the sense of smell sooner than in almost any other way. 
While leaks in sewer pipes are unhygienic in that they are con- 
ducive to undesirable atmospheric conditions, they should not be 
looked upon as the agents through which transmissible diseases 
are carried. 




Fig. 112. — Method of removing ob- 
structions from a stopped drain-pipe. 



PLUMBING 115 

To the average person the term sewer gas conveys the impres- 
sion of a particularly loathsome form of vaporous contagion, 
capable of distributing every form of communicable disease. To 
the scientific mind it means no more than a bad odor. Sewer gas 
is really nothing but ill-smelling air. 

RANGE BOILERS 

The hot-water supply to the household is of so much impor- 
tance, that the installation of the range boiler should be made 
with great care, and an understanding of the principle on which 
it works should be fully appreciated by all who have to do 
with its management. The ability of the boiler to supply the 
demands put upon it depends in a great measure on its size and 
the arrangement of its parts, but proper management is necessary 
to assure a supply of hot water when required. 

Range boilers are used for storing hot water heated by the 
water-hack of the kitchen range or other water heater, during a 
period when water is not drawn. It serves as a reserve supply 
where the heater is not of sufficient size to heat water as fast as 
is demanded. 

As commonly used, range boilers are galvanized-steel tanks 
made expressly for household use. They are standard in form 
and may be bought of any dealer in plumbing or household 
supplies. In capacity they range from 20 to 200 gallons and are 
made for either high- or low-pressure service. They are said to 
be tested at the factory to a pressure of 200 pounds to the square 
inch and are rated to stand a working pressure of 150 pounds. 
Range boilers are galvanized after they are made and coated 
both inside and out. The coating of zinc received in the galva- 
nizing process helps to make their seams tight and at the same 
time renders the surface free from rust. 

There is no definite means of determining the size of tank 
to be used in any given case, because of the varying demands 
of a household but a common practice is to allow 5 gallons in 
capacity to each person the house is able to accommodate. 

The Water-back.— The most common method of heating water 
for the range boiler is by use of the water-back or water-front of 
the kitchen range. The water-hack is a hollow cast-iron piece 



116 



MECHANICS OF THE HOUSEHOLD 



that is made to take the place of the back fire-box Uning of the 
range. In some ranges the heater occupies the front of the 
fire-box instead of the back, in which case the heater becomes 
the water-front. 

The arrangement of pipes connecting the source of water 
supply with the boiler is such that cold water is constantly 
supplied to the tank as the hot water is drawn. If no water is 

drawn from the tank, it will continue 
to circulate through the tank and 
heater, the water becoming constantly 
hotter. 

The connecting pipes are usually of 
iron but sometimes pipes of copper 
or brass are used. The joints should 
be reamed to remove the burr that 
is formed in cutting. The angles 
should be 45-degree bends or better 
still 90-degree bends in connecting the 
heater with the tank so as to cut down 
the amount of friction as much as 
possible. 

In Fig. 113 is shown a standard 
range boiler connected to the range. 
The water is brought into the top of 
Fig. 113. — a common the tank through the pipe a~a, and 
method of connecting the range passing through it enters the water- 

boiler to the water-back. i i i /• i '7 

back by means oi the pipe o. After 
passing through the water-back the water again enters the tank 
through the pipes c and d, as indicated by the arrow. The 
flow pipe (carrying the out-going water) from the water-back 
may be connected with the tank at 6, as shown dotted or in 
some cases the connections are made at both places. The veloc- 
ity of circulation depends on the vertical height of the column 
of hot water and the greater height will, therefore, improve the 
circulation and thus increase the efficiency of the heater. The 
circulation of the water through the tank and heater is pro- 
duced by its change in weight as the water is heated. As the 
hot water comes from the water-back it rises in the pipe because 
it is lighter in weight than the cooler water of the tank. In 




PLUMBING 117 

the case of the pipe shown dotted in Fig. 113 the longer ver- 
tical rise will give a greater upward velocity of the hot water 
and consequently a better circulation through the entire circuit. 

The construction of the water-back is shown in the small 
drawing. The connections are made at h and c as before. A 
division plate in the water-back causes the water flowing in at 
h to follow the length of the heater at the bottom and return at 
the top as indicated by the arrow, when it is discharged at C. 

The hottest water is always at the top of the tank and the 
temperature grades uniformly from the hottest at the top to 
the coolest at the bottom. The reason for extending the pipe 
a so far down into the tank is that the cold water may not 
mingle with the hot water and reduce its temperature on entering 
the tank. Near the top of the pipe a is a small hole / that is in- 
tended to prevent the water from being siphoned from the tank 
in case a vacuum is formed in the cold-water pipe. In this ar- 
rangement the water enters and leaves at the top of the tank. 
In case the supply is shut off at any time the tank is left almost 
full of water, because the siphoning effect cannot extend below 
the small hole /. 

Excessive Pressure. — Accidents due to the explosion of hot- 
water backs are not at all rare and it should be borne in mind 
that there is danger of excessive pressure being formed should 
the pipes h and c become stopped. Under normal conditions 
the pressure generated by the heated water is relieved by the 
water in the tank being forced back into the supply pipe. The 
pressure in the tank, therefore, cannot become greater than that 
of the source of supply, but if h and c should become stopped 
with the water-back full of water a dangerous pressure might 
result. The greatest danger from this cause is that of freezing. 
It frequently happens that houses are closed during cold weather 
and the water-back is left undrained. The water freezes and 
when a fire is started in the range, the ice in the water-back 
is the first to melt. In a short time steam will be generated that 
will soon produce a sufficient pressure to burst the water-back. 
This has happened many times with disastrous results. Such 
dangers may be avoided by the exercise of a reasonable amount 
of care in the management of the range. To drain the water- 
back, the water is first shut off at the point where the supply 



118 



MECHANICS OF THE HOUSEHOLD 




Hot 
Water 

t 



\p==^ 



Fig. 114.— Blow-off 
for removing sedi- 
meDt. 



pipe enters the house. The water in the range boiler is then 
drawn off by means of the cock h. 

Blow-ofif Cock. — When a considerable amount of sediment 
is carried in the water the range boiler acts 
as a settling tank and the deposit accumu- 
lated at the bottom will in time amount to 
a source of trouble. The 
accumulation is shown in 
Fig. 114. The part W, 
which connects with JS, 
is sometimes provided 
with a blow-off cock 
that will admit of a dis- 
charge of the sediment. 
More commonly the 
piping is arranged as 
shown in Fig. 113, when 
sediment is removed by 
occasionally drawing 
water from the cock h. 

Location of Range Boiler.— It is some- 
times desired to place the range boiler on a 
different floor, either above or below the 
range. While such arrangements are entirely 
possible the circulation of the water is not so 
good as that described above. The weight 
of the two columns of water in the connecting 
pipes are so nearly balanced that good cir- 
culation is not always possible. In Fig. 115 
the connections are shown, where the tank 
is located in the basement. In connecting 
the water-back to the tank under such con- 
ditions the piping is relatively the same 
as is shown in the dotted connections of Fig. 
113, but the -connections are longer. The 
circulating pipe comes from the bottom of 
the tank and leads to the bottom of the water-back. The flow 
pipe from the top of the water-back is extended up to a distance 
equal or greater than the distance from the water-back to the 



Water 



<9^ 




Fig. 115.— Method 
of connecting the range 
boiler when placed on 
the floor below the 
heater. 



PLUMBING 



119 



bottom of the tank. The hot water is taken from the top of 
the flow pipe at any place above the tank. 

Double Heater Connections. — Two heaters are sometimes con- 
nected to one range boiler, each circuit being independent of 
the other. Under such conditions one or both heaters may be 
used. When the tank is connected as shown in Fig. 116 the pipe 
a, from the bottom of the tank, branches and leads to h and h\ 
at the bottom of each of the heaters. The flow pipes from the 
top of the heaters enter the tank at separate places, the lower 
heater sending its water into the side of the 
tank at c, and the upper heater flowing into 
the pipe d, at the top of the tank. It would 
be perfectly possible to reverse the connec- 
tions for the flow pipes in the arrangement 
of Fig. 116 and attain the same results. 
In such combinations the heaters are some- 
times piped tandem, the water flowing 
through each of the heaters in turn. This, 
however, is not the best method to employ, 
for if only one of the heaters is used the 
second acts to cool the water. 

Horizontal Range Boilers. — It occasion- 
ally happens that in a small kitchen there 
is no convenient floor space for the range 
boiler and it becomes necessary to suspend 
it from the ceiling. It is perfectly possible 
to station the ordinary range boiler in such 
a position and have it work fairly well but 
from the location of the cold-water inlet, 
only that part of the range boiler above the 
cold water pipe is actually used for storage. 
The water in the lower half constantly mixes 
with the entering cold water before it is 
heated by passing through the water-back. When hot water 
is drawn from the top of the range boiler, cold water enters by 
the cold-water pipe and reduces the temperature of most of the 
lower half. Fig. 117 illustrates such an arrangement. In this 
case the pipes connected with the water-back are those that cor- 
respond to the circulating pipes a and e in Fig. 113. 




Fig. 116.— Double 
connections for the 
range boiler where a 
heater is placed in 
the basement for oc- 
casional use. 



120 



MECHANICS OF THE HOUSEHOLD 



Suppose the range boiler is full of water, and that it is being 
heated. The lower pipe at the left-hand end is conducting the 
water to the water-back and it is being returned to the range boiler 
by the upper pipe at the same end. When the hot water is 
drawn from the top of the range boiler by the hot-water pipe, 
the entering cold water mixes with hot water in most of the 

lower half of the range boiler 
before it has been heated by 
passing through the water- 
back and so reduces the tem- 
perature of most of the lower 
half of the tank. 

A much better tank for the 




d: 



^ . Hot 



^ ^ 



_Cold 
Water 



Fig. 117. — Method of con- 
necting the vertical range-boiler 
in a horizontal position. 



Fig. 118. — Horizontal range-boiler sus- 
pended from the ceiling. 



purpose is that indicated in Fig. 118. This is a tank made 
particularly for such a location. The cold water enters at the 
bottom of the tank and also leaves the bottom on its way 
to the water-back. Circulation takes place through the water- 
-back as before but when hot water is drawn from the top of 
the tank, the entering cold water at the bottom mixes with only 
that at the lower part of the tank and so cools but a small 
amount of the hot water in storage. Hot- water tanks of this 
kind are tapped for pipe connections in two places on both the top 
and bottom sides and also at the ends as shown in the drawing. 



PLUMBING 



121 



Tank Heaters.— When the demand for hot water is sufficient 
to warrant a separate hot-water heater the apparatus similar 
to Fig. 119 is used. With such a heater, the conditions of over- 
heated water — to be described later — may be almost entirely 
avoided. In this case the connections are arranged similarly to 
those of the range boiler but a separate furnace takes the place 
of the water-back. The heater is simply a small furnace made 
expressly for heating water. Connected with the discharge pipe 
p is a draft-regulating valve which controls the drafts of the 
heater. The draft-regulator is set to so con- 
trol the furnace that water at the desired 
temperature will always be in the tank. 
The mechanism of this regulator is the same 
as the draft-regulator described under hot- 
water heating plants. 

Overheated Water. — Under ordinary con- 
ditions the water contained in the range 
boiler is below the atmospheric boiling point 
(212°F.) but at times when a hot fire is kept 
up in the range for a considerable period, the 
temperature will rise to a degree much above 
that amount. The temperature to which 
the water will rise will depend on the pres- 
sure of the water supply. As an example 
— suppose the gage pressure of the water 
supply is 25 pounds. The temperature cor- 
responding to that pressure is 258°F. The 
temperature of the water in the tank will rise to that amount 
but not further because any additional temperature will produce 
a higher pressure, but a higher pressure would be greater than the 
pressure of the water supply and hence will back the water into 
the supply pipe. This condition of things, then, acts as a safety 
valve to the tank to prevent excessive pressures. 

When the water at a high temperature is drawn from the tap a 
considerable part of it will instantly vaporize, because of the 
reduced pressure. If water at a pressure of 25 pounds is drawn 
from the faucet, the temperature, 258°F., is sufficient to send all 
of the water instantly into steam. This high temperature will 
scald at the slightest touch. The water drawn from the faucet 




Fig. 119. — Indepen- 
dent hot-water heater 
with temperature regu- 
lator. 



122 



MECHANICS OF THE HOUSEHOLD 



will continue to vaporize as it comes into the air until the water 
in the tank is cooled by the incoming cold water. The only 
means of relieving the overheated condition is to open the faucet 
a slight amount and allow a portion of the heated water to be 
drawn off. 

It is evident from what has been said of the range boiler that 

it operates under a variety of condi- 
tions. It is first a storage tank in 
which is accumulated the water, heated 
from a greater or less period of use of 
the range. Should the range fire be 
maintained through the day or night 
the supply of hot water will be excessive 
and superheating is the result. If the 
heater is to be used during short periods 
of time, the piping should be arranged 
to produce the best circulation; on the 
contrary, should the heater be used con- 
tinuously — as in the case of a furnace 
coil — a slow circulation through the 
tank is most to be desired and the 
piping should be arranged for that 
purpose. 

In the use of furnace heaters, super- 
heating is likely to occur during cold 
weather when a hot fire must be used 
over a long period of time. In order 
to conserve the heat accumulated under 
such conditions a hot-water radiator 
is frequently connected with the range 
boiler through which to dispose of the 
excess heat. This radiator may be 
placed in any desired position and so 
connected by a valve as to discontinue 
its use at any time. 
Furnace Hot-water Heaters. — It is sometimes more con- 
venient to use the furnace as a means of heating water than the 
kitchen range. Such an arrangement is shown in Fig. 120, 
where a loop of pipe in the fire-box of the furnace takes the place 




Fig. 120. — The range boiler 
connections when a furnace 
coil is used for hot-water heat- 
ing. 



PLUMBING 123 

of the water-back. The arrangement of the pipes in the range 
boiler are as before, the water entering the tank through the 
pipe A J circulates through the pipes B and C, receiving its heat 
while passing through the loop in the furnace, in exactly the 
same way as in the water-back. It would be quite possible to 
also connect the kitchen range with the tank as shown by the 
dotted lines indicating the water-back. Such an arrangement 
would virtually be that shown in Fig. 116, where the two heaters 
on different floors are connected with the boiler. 

Instantaneous Heaters. — In isolated bathrooms where no con- 
stant supply of hot water is available, instantaneous hot-water 
heaters are much used. In many houses where a range fire is 
used intermittently, particularly during the summer months, 
a like method is used for the hot-water supply. These heaters 
are made in many forms to suit any condition. Some are very 
simple, being made of a gas heater, the heat from which is held 
against a long coil of pipe or a large amount of heating surface 
in other form, through which the water circulates on its way 
to the tap. Others are quite elaborate, being made entirely 
automatic in their action. The Ruud heater, for example, is 
so constructed that when the hot-water faucet is opened the 
reduced water pressure starts a gas heater in contact with a 
series of pipe coils through which the water circulates. As soon 
as the water faucet is closed the water pressure automatically 
closes the gas valve, cutting off the supply of gas. A little gas 
jet used for igniting the burner is left constantly burning, ready 
to light the gas whenever hot water is required. 

Fig. 121 illustrates a simple form of instantaneous heater that 
is relatively inexpensive and has met with a great deal of favor. 
A sheet-iron casing encloses a siauous, multiple coil of pipes 
through which the water passes. The heat furnished by a Bun- 
sen burner of a large number of small jets is evenly distributed 
over the bottom of the heater. The heating coils are arranged to 
interrupt the heat passing through the casing and absorb as 
much as possible. To do good work such a heater must be 
connected by a pipe to a chimney flue which furnishes a good 
draught. 

Instantaneous water heaters should not be used in bathrooms 
unless the products of combustion from the heater are carried 



124 



MECHANICS OF THE HOUSEHOLD 



away by a chimney. The combustion of the required amount 
of gas produces a large volume of carbonic acid gas which if 
allowed to remain in the room is not only deleterious but may be 
a positive danger to life. Cases of asphyxiation from this cause 
are not at all rare. 



Discbarge f .Chimuey 

Pipe nq 1 



IJ-iiFiiTriiiK ' 




~^ Supply 
Bunsen Burner 

JGas 

Fig. 121. — Gas heater for hot- 
water supply. 




Fig. 122. — Hot-water supply with 
gas heater, ^ connected to the range 
boiler. 



Fig. 122 shows the heater connected with a range boiler. 
In this case the heater may be considered as taking the place 
of the water-back. It may, however, be used as an auxiliary 
heater. In the picture of the kitchen shown in Fig. 80, an 
instantaneous heater is shown attached to the range boiler. 
It is located in this case between the kitchen range and the 
boiler. 



CHAPTER VII 
WATER SUPPLY 

The use of water enters into each detail of the affairs of 
everyday life and forms a part of every article of food; its 
quality has much to do with the health of the family, and its 
convenience of distribution lends greatly to the contentment of 
its members. The family water supply should be as carefully 
guarded as means will permit, and judicious care should be 
exercised to prevent the possibility of its pollution. Where 
the source of the water is known, it should be the subject of 
unremitting attention. 

Water comes originally from rain or snow and as it falls, it 
is pure. Water, however, in falling through the air absorbs the 
contained vapors and washes the air free from suspended organic 
matter in the form of dust, so that when it reaches the earth 
rain water contains some impurities. 

As the water is absorbed by the earth, it comes into contact 
with the mineral matter and organic materials of animal and 
vegetable origin contained in the soil; and as water is a most 
wonderful solvent, it soon contains mineral salts and possibly 
the leachings from the organic substances through which it 
passes. The impurities usually found in well water are in the 
form of mineral salts that have been taken up from the earth, 
but other contaminating materials may come from the surface 
and be carried into the well by accidental drainage. 

Water that is colorless and odorless is usually considered good 
for drinking and in the absence of more accurate means of 
determination may be used as a test of excellence; but it often 
happens that water possessing these qualities is so heavily 
freighted with mineral salts as to be the direct cause of impaired 
health. Again, water that appears pure may be polluted with 
disease-producing bacteria to such an extent as to endanger 
the lives of all who use it. The fact that a source of drinking 

125 



126 MECHANICS OF THE HOUSEHOLD 

water bears a local reputation for purity, because of long usage, 
cannot be taken as a test of its actual purity until it has been 
subjected to chemical and bacterial examination. 

It must not be inferred that all water is likely to be unsuitable 
for drinking; there is, however, a possibility of the water being 
polluted from natural sources and from accidental causes, that 
are sometimes preventable; and the only means of determining 
the purity of water is by chemical and bacterial examining. 

Water Analysis. — In order to be assured as to the quality of 
drinking water, it should be subjected to analysis and the result 
of the analysis inspected by a physician of good standing. Such 
analysis may usually be obtained free of charge from the State 
Board of Health and if asked, the Chief Chemist will usually give 
his opinion regarding the quality as drinking water. 

In chemical water analysis, the total amount of solids, regard- 
less of their nature is taken as indicative of its excellence for 
drinking purposes. These solids may be either in suspension 
and give the water a color or produce a turbidity, or they may 
be entirely in solution and the water appear colorless. English 
authorities on the subject place the allowable proportion of 
solids at 500 parts to the million. Any water that contains 
more than 500 parts to the million is condemned for drinking 
purposes. Water containing 500 parts or less to the million 
is considered good. The Standard of the American Board of 
Health permits the use of water for city supply that contains 
1000 parts of solid matter to the million. 

The amount of solids contained in water is not at all a definite 
indication of its quality for drinking purposes, as may be inferred 
from the widely varying amounts permitted by the different 
authorities, but it gives an indication of its character because of 
the known physiological action of the contained solids. 

Chemical analysis alone cannot be taken as a complete indica- 
tion of the character of water, because such analysis shows 
nothing of the bacteria that may be present. The organic matter 
may indicate the possible presence of bacteria, but microscopic 
examination will be required to determine its harmful properties. 

As examples of the chemical constituents of potable waters, 
the following furnish illustrations of different types of water in 
general use. 



WATER SUPPLY 127 

Pokegama Water. — The water from Pokegama Spring at 
Detroit, Minn, is used widely through the Northwest as a table 
water. It is considered to be a very excellent drinking water 
because of the low amount of solids and the absence of any 
deleterious constituents. The complete chemical analysis as re- 
ported by the North Dakota Pure Food Laboratory is as follows: 

Grains per gallon 

Sodium chloride . 0200 

Sodium sulphate . 0357 

Sodium carbonate 3 . 9288 

Calcium carbonate 11 . 3997 

Lime carbonate . 0016 

Magnesium carbonate 3 . 8896 

Sodium phosphate trace 

Potassium sulphate . 4435 

Silica 0.4416 

Organic matter . 1006 

Total 20.2611 

The total solids, 20.2611 grains per gallon, equivalent to 346.85 
parts per million, is very low and composed of carbonates of 
sodium, calcium and magnesium, none of which are in any way 
harmful even in much larger quantities. The amount of organic 
matter is practically nothing. 

River Water. — The water supply of the city of Fargo, N. D., 
is taken from the Red River of the North, which after being 
filtered through a mechanical filtration plant is supplied to the 
water system of the city. The river water in its raw state is 
considered unfit for drinking because of the amount of organic 
matter present at different times of the year. 

Analysis of raw water from intake pipe, April 14, 1913: 

Parts per million 

< Chlorine 10 

Equivalent as sodium chloride, sarlt 16 

Volatile and organic matter 80 

Mineral solids 180 

Total solids 260 

In this water neither the solids nor the organic matter are at 
all high but during a part of each year there are many pathogenic 



128 MECHANICS OF THE HOUSEHOLD 

germs present, the contained typhoid bacillus being the most 
feared. The following is an analysis after the water has been 
filtered, April 14, 1913: 

Parts per million 

Chlorine 12 

Equivalent as sodium chloride, salt 18 

Volatile and organic matter 45 

Mineral solids 140 

Total solids 185 

It will be noticed that in the process of filtration there has been 
removed from the water 35 parts to the million of organic matter 
and with probably 99 per cent, of the pathogenic bacteria. In 
addition there has been removed 40 parts to the million of min- 
eral solids, the removal of which has changed a very hard water 
to that which is reasonably soft. The process of filtration has 
changed water that is generally condemned for drinking to one 
that is considered remarkably good. 

Artesian Water. — The analysis of the sample of artesian water 
given below is an example of the water analysis made by the 
North Dakota Pure Food Laboratory. It furnishes an illustra- 
tion of the type of reports that are returned from samples of 
water submitted for examination. This report was in the form 
of a letter which was taken at random from the files of the 
laboratory. 

Sample of artesian water No. 1936 from Moorhead, Minn. : 

Parts per million 

Chlorine 70 

Equivalent as sodium chloride, salt 116 

Volatile and organic matter 90 

Mineral solids 455 

Total solids 545 

^^The solids in this water are made up of sodium chloride, salt, 116 
parts; volatile and organic matter, 90 parts; lime sulphate, a trace; 
lime carbonate, a slight amount; magnesium carbonate, a slight amount; 
and the balance of the solids are all wholly made up of sodium bicar- 
bonate. This water is low in solids and of good quality.'' 

Medical Water. — The solids that occur most commonly in 
spring and well water appear in the form of mineral salts. It 



WATER SUPPLY 129 

frequently happens that salts giving a cathartic action are pres- 
ent in sufficient quantity to render the water objectionable when 
used for drinking. Sodium chloride or common salt frequently 
occurs in quantity sufficient to be distinctly noticeable. Mag- 
nesium sulphate (Epsom salts) and sodium sulphate (Glauber 
salts), both of which are well-known laxative salts, very commonly 
occur in well water. The carbonates of calcium and sulphur 
also frequently found in well water are inert in physical action 
when taken in drinking water. The presence of laxative salts 
in spring water has given great celebrity to many springs both 
in Europe and America that are famous as cures for all manner 
of human ills. Such curative value as these springs possess is 
derived from the cathartic salts contained by the water. 

The table of contents of the Saratoga Congress Water as given 
by Dr. Woods Hutchinson shows the solids of one of the most 
celebrated of America's medicinal waters. 

Grains per gallon 

Sodium chloride 385 

Magnesium carbonate 56 

Calcium carbonate and sulphate 116 

Sodium bicarbonate 9 

Sodium iodide 4 

Bromide, iron, silica ^ trace 

Total soHds 570 

When reduced to ordinary measure and given their com- 
mon names the mineral solids in a gallon of this water will be 
approximately : 

Common salt 8 teaspoonf uls 

Magnesium 1 teaspoonf ul 

Lime and plaster of Paris 2 teaspoonf uls 

Baking soda H teaspoonful 

Bromides and iodides H2 teaspoonful 

The total solids, 570 grains per gallon, contained in Saratoga 
water, gives the remarkably high content in total solids, of 9758 
parts per. miUion; this is almost ten times the Hmit of the Ameri- 
can standard. While such water would not do for constant con- 
sumption, it is taken for considerable periods of time with benefi- 
cial results and is recommended by many authorities as a water 

of great medicinal potency. 
9 



130 MECHANICS OF THE HOUSEHOLD 

While most medical authorities condemn the use of water high 
in solids, the ideal drinking water is neither soft water nor 
distilled water — that is, water that is perfectly free from any 
saltiness — but one that contains a moderate amount of the ordi- 
nary constituents of the earth. It is reasonably safe to assume 
that any unpolluted water containing as high percentage of solids 
as 1000 parts of total solids to the million, and that is agreeable 
to the taste, would be safe for drinking. 

'^ Chemical analysis in general indicates the possible pollution of 
water. A relatively high content of organic substances, nitrate, 
chlorides and sulphates, might indicate contamination, particularly 
when ammonia is also present. On the other hand, a high content 
of just one of the above-mentioned substances, be it organic, chloride, 
nitrate or sulphate, may originate from the natural soil strata/' 

Organic Matter. — Organic matter may come from peat 
swamps, decaying leaves and grasses; or it may come from 
decayed animal matter which finds its way into the soil; or 
worst of all it may come from cesspools or other sewage. While 
the presence of organic matter does not necessarily indicate the 
presence of disease-producing bacteria, it is a medium in which 
such germs live and multiply; for that, reason it is an indicator 
of possible harm. 

^^ Waters containing a high percentage of organic substances and 
among them products of putrefaction are frequently used without 
damage but they are capable of producing gastro-intestinal catarrh, 
phenomena of excitement and paralysis as well as death. Of the many 
pathogenic bacteria that sooner or later may get into the water, those of 
cholera and typhoid are of special importance. 

^'Pathogenic bacteria occur but rarely and when once they find their 
way into a water, they generally do not multiply but remain for a greater 
or lesser period viable. 

'^ Bacteria enter wells by three different modes: first, from surface 
water that is washed from the soil by rain; second, from faulty construc- 
tion of the curbing; and third, from bacteria entering the soil from vaults, 
etc.'' (Van Es). 

Ammonia. — In the analysis of water the presence of ammonia 
is an indicator of organic matter. Ammonia is not of itself 
injurious but it indicates the presence of matter in which bacteria 



WATER SUPPLY 131 

find conditions suited to their growth. Free ammonia is usually 
considered an indicator of recent pollution, while albuminoid 
ammonia indicates the presence of nitrogenous matter that 
has not undergone sufficient decomposition to form ammonia 
compounds. 

Hardness in Water. — Water that holds no mineral matter in 
solution is '^soft water'' and when soap is added will readily form a 
lather. The presence of lime or magnesia is commonly the cause 
of ''hardness'' in water. Either of these minerals, when pres- 
ent form an insoluble curd when the soap is added to the water 
and the soap will not form a lather until enough soap has been 
added to unite with the mineral matter present. The hardening 
agents are usually in the form of bicarbonates and sulphates. 
All soap used in neutralizing the hardening agents is wasted, 
because a lather will not form until all of the hardening materials 
are neutralized. It is evident that the softening of water for 
domestic purposes is beneficial, both because of the less amount 
of soap required and because of the absence of the curd. 

Hardness in water may occur in two forms — as temporary 
hardness or as permanent hardness. When bicarbonate predomi- 
nates as the hardening agent, the water is said to be temporarily 
hard because, when heated to boiling, the bicarbonate is precipi- 
tated and the water is thus softened. When softening of such 
water is to be done on a large scale, chemical treatment is 
more satisfactory. Water containing bicarbonate of lime may 
be softened by adding a pound of lime to 1000 gallons or 1 pound 
of lime to 165 cubic feet of the water. This quantity of lime 
is sufficient to remove 10 grains of the bicarbonate to the gallon. 

When the mineral matter is in the form of sulphates, mainly 
sulphate of lime or magnesia, the water is said to be permanently 
hard, because boiling will not soften it. Such water may be 
softened by adding soda ash or impure carbonate of soda. One 
pound to l^i pounds of ''washing soda" to each 1000 gallons 
of water will render such water soft; by its action the sulphate 
of lime is precipitated and settles to the bottom of the container; 
the water may then be siphoned off leaving the precipitate in 
the bottom. 

Iron in Water. — ^ Water containing iron is found in many wells 
and springs. While iron is not harmful, it is objectionable to 



132 MECHANICS OF THE HOUSEHOLD 

taste and stains most things with which it is long in contact. 
It may be precipitated with Hme and removed as the sulphate 
of magnesia described in the preceding paragraph. 

Water Softening with Hydrated Silicates. — By W. L. Stock- 
ham, assistant chemist, North Dakota Experiment Station. 

^'The use of chemicals in softening water requires the mechanical 
removal of the separated materials by skimming, settling or filtering 
and it is difficult to determine just how much chemical to add. A new 
process for softening water, and one that has awakened great interest 
because of its efficiency, employs hydrated silicates of aluminum or 
iron combined with soluble bases. This process softens water from 
practically any condition or hardness. 

''The form of apparatus in use varies from a portable jar, with an 
inlet at the top and an outlet at the bottom, to the more complex 
tanks for industrial and domestic purposes. A plant for domestic 
use might consist of a 20-gallon tank for containing the softening mate- 
rial and a second tank in which is prepared the salt solution for reacti- 
vating the softener. The two tanks with their valves and connections 
constitute the apparatus. The softener, supported by a porous plate, 
sieve, or layer of gravel, completely fills the first tank and the water 
to be treated passes through the interspaces between the granules, 
ki some plants the water passes through a layer of marble chips before 
coming into contact with the softener. The apparatus may be attached 
temporarily to the faucet or connected permanently with the water 
system. A gravity system may be employed where the water pressure 
is lacking. 

''The softener is put on the market in granular form and may be 
purchased and used with apparatus other than that furnished by manu- 
facturers. The granules are about 3^ inch in diameter and permit 
a ready passage of the water through the interspaces. The material 
lasts indefinitely. 

"As the water passes through the apparatus, the large exposed 
surface of the granules entirely absorbs the calcium and magnesium, 
which produce hardness, making it soft and ready for immediate 
use. The water does not require being in contact with the softener 
any longer than the time taken to pass through and it emerges almost 
as fast as from the faucet. The softener must be reactivated after 
it has softened a certain amount of water. This is accomplished by 
filling the tank with a common salt solution which is contained in the 
second tank. The water supply is temporarily shut off and the salt 
solution allowed to fill the softening tank. After remaining in contact 



WATER SUPPLY 133 

with the granules for a time the chemical action of the salt releases the 
calcium and magnesium, which are flushed out with the excess of salt 
solution, into the sewer. The softener thus renewed is ready for soften- 
ing another supply of water. Since this renewal is a simple appUcation 
of the law of mass action, an excess of the salt must be used. The 
renewal may be repeated indefinitely. 

The amount of any particular sample of water which can be softened 
before renewal depends on the amount of material in the apparatus 
and the hardness of the water. Five gallons of the water per pound 
of softener would not be far from the average capacity. Where a 
large amount of soft water is required at one time, it may be prepared 
in advance and accumulated in a tank or cistern. 

^^The cost of softening, aside from the original cost of the plant, is 
nominal, as the value of the salt solution is the only expense. 

^^The water produced by this process is absolutely soft and suitable 
for drinking, domestic and industrial purposes. In the case of very 
hard water the saving in soap for washing is more than equal to the 
cost of operation. There are at least three firms manufacturing soften- 
ing plants of the kind at the present time: The Permutite Co. of New 
York; the Cartright Co. of Chicago, whose product is called Borromite; 
and the Des Moines Refining Co., manufacturers of Refinite. 

'^A comparative test of various forms of water-softening materials 
may be obtained from the Regulatory Department, North Dakota 
Agricultural College. '' 

Chlorine. — The presence of chlorine in water may indicate 
the presence of polluting matter in the form of sewage but only 
when the amount is considerably above the normal amount of 
chlorine that is contained in the soil in the community from 
which the water is taken. An increase of the chlorine in the 
water would indicate a probable pollution from sewage. ♦ 

Polluted Water. — Well water that is roily or that possesses ob- 
jectionable taste or odor may be suspected of containing pol- 
luting matter and should be boiled before being used for drinking 
porposes until such time as may be required to have it examined. 
Sickness due to the use of polluted water does not necessarily 
develop as specific diseases, unless the water contains disease- pro- 
ducing bacteria. Typhoid fever, one of the commonest and most 
dreaded of diseases, is usually transmitted by water. Typhoid 
is a disease of human origin, the germ of which develops in 
the elementary tract of the human kind alone. The germs may 



134 



MECHANICS OF THE HOUSEHOLD 



be spread by the waste from the typhoid patient by being thrown 
on the ground where it is taken up by the water and passes into 
streams or it may enter wells from privies or cesspools. A 
single case of typhoid has been known to so pollute the water of a 
stream, as to produce an epidemic of the disease throughout the 
entire length of the stream, among the people who drank its 
water; while water from a polluted well often transmits disease 
to a neighborhood. 

Pollution of Wells. — ^The water from wells is often polluted 
by seepage through the earth from sources that might be pre- 
vented. Fig. 123 illustrates some of the commonest sources of 
contamination that through carelessness or ignorance are located 
in the neighborhood of the family water supply. The drainage 







Fig. 123. — Some of the common causes of pollution of wells, and the means of 
transmitting disease, such as typhoid, etc. 



from such sources of pollution is often directed toward the well 
and many cases of ill-health, disease or death are the direct 
consequences of drinking its water. It may be readily observed, 
in the case of the well illustrated, that the more water that is 
pumped from the well, the greater will be the tendency of the 
water from each of the sources of pollution to reach the well. 

Another common cause of contamination of well water is that 
of imperfect well curbs that allow the waste water or surface 
water to flow into the well. The area about the well should be 
graded to allow no standing water, and the waste should be con- 
ducted away without permitting it to collect in standing pools. 

Drainage from manured fields or other places where disinte- 
grating animal or vegetable matter may be absorbed by water is 



WATER SUPPLY 135 

often the cause of temporary pollution, where the water is carried 
to low-lying wells. Wells located in low areas that receive the 
drainage from such places may be suspected of pollution during 
the spring or early summer, when during the remainder of the 
year the water is pure. 

In connection with any water suspected of pollution, it is well 
to remember that by boiling the water used for drinking, its 
harmful properties are entirely destroyed. 

Safe Distance in the Location of Wells. — In the location of a 
well, the distance of safety from sources of pollution will depend, 
in a considerable measure, on the character of the soil and the 
quantity and concentration of the pollution material entering 
the ground water. When coming from the surface, the danger 
is usually neither great nor difficult to avoid; but when cesspools 
and privies in the neighborhood are sunk to a considerable depth 
in porous earth, from which the supply of water is drawn, the 
polluting material may reach the well undiluted. No absolute 
radius of safety can be given, but certain generalizations as to 
conditions may be made as to character of soil and the different 
topographical conditions which surround a safe location. 

In ordinary clay, or in clay mixed with pebbles and in soils of 
the same general nature, through which the water circulates by 
seepage, the pollution is not likely to be carried to a distance of 
100 feet. Clay offers marked resistance to the passage of water, 
which in beds of 3 to 5 feet thick will act as protection from pollu- 
tion from above. In sandy soils the movement of water is faster 
than in clayey soils, but 150 feet may be taken as a safe distance, 
unless the downward slope of the land carries the polluting ma- 
terial directly to the well. 

Surface Pollution of Wells. — In dug wells, pollution from the 
surface is due most commonly to careless construction and lack 
of care. In Fig. 124 is indicated the most common cause of 
surface pollution. The figure represents a well that has been 
curbed with planks. Through lack of care the earth has sunken 
at the top, permitting the surface water to flow into the well. 
The top of the well is on a level with the surface and covered 
with loosely laid boards which allow the waste water to (h'ip 
through the joints. Such a well, even though the source of 
supply is good, will likely yield water of inferior quality. 



136 



MECHANICS OF THE HOUSEHOLD 



In bored wells, polluting water may enter through the unce- 
mented joints of the tiling or through the joints in the staves of 
wooden tubing; in drilled or driven wells, through leaky joints 
or holes eaten in the iron casing by corrosive waters. By ce- 
menting the interior surface of stone- or brick-curbed wells, by 
replacing wood with cement or other impervious curbs and 
by substituting new pipes for leaky iron casings, the entrance 
of polluting water may be prevented. 

In the average home the water supply is most commonly 
taken from a well, the water from which comes through the 

earth from unknown sources, and 
the character of chemical salts 
or organic matter the water con- 
tains will depend on the kind of 
soil through which it passes before 
reaching the well. 

The water from wells, whether 
deep or shallow, is generally of 
relatively local origin, it being ab- 
sorbed by the soil and carried to 
the water stratum by percolation. 
If the soil contains soluble min- 
eral salts the water will contain 
these materials in quantities de- 
pending on the amount of the 
salts present in the earth. If 
the earth contains organic matter 
as pathogenic bacteria the water 
is likely to contain these bacteria in like numbers as they are 
present in the soil through which the water filters. 

As usually encountered, the water-bearing earth occurs in 
sheets rather than in veins or streams. The movement of the 
water in such areas follows the contour of the earth and is 
influenced by the varying amount of rain or snowfall and the 
atmospheric pressure. The lateral movement is often only a 
few inches a day and in some places no lateral movement occurs 
at all. Underground streams of any kind are not usually found 
except in limestone regions. 

As a rule, a well is formed by digging or boring into the earth 




Fig. 124. — Undesirable form of 
well curbing. 



WATER SUPPLY 137 

until a stratum of water-bearing soil is encountered, the type of 
the well being determined by the character of the earth and the 
location of the water-bearing soil. The water from the surround- 
ing area fills the opening to the height of the saturated soil. 
As the water is pumped from the well it is replenished by the flow 
from the surrounding earth. If the soil is porous, as in the case 
of gravel, the water will refill the well almost as fast as it is taken 
away by the pump. If the soil is dense and the inward flow is 
slow, the well when once exhausted may be a long time in refilling. 

Water Table. — The upper level of the saturated portion of 
the soil is known as the water table. It has a definite surface 
that conforms to the broader surface irregularities. While a 
definite, determinable water table appears only in porous soil, 
it exists even in dense rocks. It rises and falls in wet seasons 
and in drought. In exceptionally wet seasons the water table 
may be at or above the surface. Under such conditions the op- 
portunities for the pollution of wells is much increased. In 
particularly dry seasons the water table may sink below the 
bottom of the well, when it is said to ^'go dry.'' The water 
table follows the surface contour in a manner depending on the 
character of the soil. It is flatest in sand or gravel areas but in 
clay it follows the contour of deep slopes with but slight variation. 

The Devining Rod. — The use of the devining rod, for the 
purpose of locating suitable sites for wells, has been supposed by 
many to be a gift possessed by a chosen few. The devining rod 
is a forked branch of witch hazel, peach or other wood, which 
when held in the hands and carried over the ground, is supposed 
to indicate the presence of water by bending toward it. 

In most cases the operators are entirely honest in their belief 
and in a large proportion of trial their efforts have been successful 
in locating desirable wells; but it has many times been proven 
that the movement of the rod is due to an unconscious muscular 
movement of the arms and hands, in places where the operator 
has previously suspected the presence of water. The operator 
of the devining rods is most successful in regions where water 
occurs in sheets, such as often occur in gravel or pebbly clay. 
The successful use of the devining rod cannot be explained by 
any scientific reasons. There have been invented a number 
of devining rods, claimed by their inventors to be based on 



138 MECHANICS OF THE HOUSEHOLD 

scientific laws; but the government has not yet granted patents 
to appHances of the kind. 

Selection of a Tjrpe of Well. — The chief factor which controls 
the selection of a type of well is the nature of the water-bearing 
earth, the amount of water required, the cost of construction 
and the care of the resulting supply. 

If a large amount of water is to be demanded of a well, to be 
dug in soil through which the water percolates slowly, the well 
must be large in diameter, in order that the necessary supply may 
be accumulated. If the earth is porous and yields its water 
readily, a small iron pipe driven into the ground may supply 
the desired amount. 

The character of the water-bearing material is of the greatest 
importance in determining the yield of the well. In quicksand, 
water is usually present in ample quantities, yet owing to the 
extremely fine particles of which the quicksand is composed, 
its presence as a water-bearing soil is highly undesirable. 

Flowing Wells. — Flowing wells are obtained in places where 
water is confined in the earth, under sufficient pressure to lift 
it to the surface, through an opening made to the water-bearing 
stratum. These are known as artesian wells, from the fact that 
they were first used in Artois (anciently called Artesium) in 
France. In order that water may have sufficient head to lift 
it to the surface, it must be confined under impervious clay or 
other bed of earth, and with its source at a level considerably 
higher than its point of exit. The source of supply for flowing 
wells is often at a great distance. Because of the fact that 
flowing wells are shut off from the surface by an impervious 
layer of earth, the possibility of pollution from the surface is 
effectively prevented. Any contamination of the water must 
come from a distance and enter the water at its source. As 
pollution rarely extends through the ground to any great lateral 
distance, artesian waters are seldom polluted. The water from 
artesian wells often is heavy with mineral matter and in many 
cases is unfit for drinking on that account. 

CONSTRUCTION OF WELLS 

Wells are constructed by different methods, depending on the 
character of the soil in which they are sunk. Their excavation 



WATER SUPPLY 139 

is usually accomplished by one of three general methods: by 
digging; by driving a pipe into the earth until it penetrates the 
water-bearing stratum; or by boring a hole with an enlarged 
earth auger, into the water-bearing soil. Artesian wells are 
made by drilHng with a device suitable for making a small and 
very deep hole. 

Dug Wells. — In shallow wells the water seeps through the soil 
from local precipitation. Deep wells are those from which the 
water is brought to the surface through an impervious geologic 
formation, as a bed of clay or rock, and from a depth greater 
than that from which water may be lifted by atmospheric pres- 
sure. The fact that a deep well originates from a source that 
entirely differs from that of the shallow well accounts for the 
difference in chemical composition which frequently exists in the 
water from the two types of wells in the same neighborhood. 

The form of the dug well is generally that of a cylindrical 
shaft 4 feet or more in diameter and of depth depending on the 
location of the water-bearing stratum. Where the character of 
the soil is such that the seepage is slow and the water does not 
flow into the well as fast as the pump will remove it, the well must 
contain a considerable volume to supply the period of greatest 
demand. Wells of this kind are commonly walled with brick or 
stone to keep the sides in place and to prevent the entrance of 
surface waters. The top of this curb should be brought above the 
surface of the ground and should be made water-tight to prevent 
the entrance of surface waters. The space around the curb, 
at the surface, should be graded to drain the water away from the 
well. There should be no chance for the water to collect in 
pools about the well; it should be conducted away in a gutter 
to the place of final disposal. The well should be covered with a 
platform of concrete or planking which will allow no water to 
enter from the surface. 

Wells of this order are sometimes dug to great depth before 
the water-bearing stratum is encountered; this may sometimes 
be reached only after a great amount of expense and labor. The 
historic Joseph Well, near Cairo, Egypt, is an open shaft, 18 by 
24 feet in area, sunk through soUd rock 160 feet. 

Open Wells. — Open wells have long been eondomncd as insani- 
tary. The famihar open well of the ^^^^Id Oaken liuckef' type 



140 



MECHANICS OF THE HOUSEHOLD 



is an inviting receptacle for the deposit of all manner of refuse, 
which once inside remains until it is disintegrated. These wells 
become the final resting place of many small animals and all 
manner of creeping things, in search of water. The open top 
receives wind-blown matter in the form of leaves and dust, much 
of which is in the nature of polluting material. 

The Ideal Well.- — In the case of a well which yields pure water, 
every precaution should be taken to prevent its pollution. The 
ideal form of construction is that shown in Fig. 125. In this 

well, the curbing C is of heavy 
concrete that extends above the 
natural surface of the ground, to 
prevent the entrance of surface 
water, and that from seepage 
through the upper stratum of the 
soil. The reinforced-concrete top 
forms a close joint with the curb 
to prevent the entrance of waste 
water and all animal life. The 
pump is of iron, secured to the well 
cover by bolts, set in the concrete. 
The trough of concrete G con- 
ducts the waste water from the 
well to a safe distance. The earth 
about the well is so graded as to 
no water to stand in 
pools. 

Coverings of Concrete. — The use of concrete for the coverings 
of wells, cisterns and springs has become a recognized form of 
the best construction. It is not more expensive than other good 
materials and when properly executed it forms an imperishable 
protection and gives a neat appearance. The spring cover in 
Fig. 126, and the cistern top in Fig. 127 are illustrations of 
its application. 

Artesian Wells. — Artesian wells are made by boring into 
the earth until the drill reaches the artesian stratum, the in- 
ternal pressure forces the water through the opening to the 
surface. They are usually small in diameter and often of 
great depth. In some areas the artesian flow is found a few 




Fig. 125. — Ideal form of well curb- 
ing with cover and drain made of r^pyiyiif 



concrete. 



WATER SUPPLY 



141 



feet below the surface, but generally it is much deeper and 3000 
feet is not an unusual depth. 

The pressure and amount of flow from these wells is sometimes 
sufficient to permit the water being used for the generation of 
power. Small waterwheels are not uncommonly driven in this 
way and the power used for the generation of electricity for 
lighting and running small household appHances. 

Driven Wells. — In locahties where the nature of the soil 
gives opportunity, wells are made by driving a pipe to the re- 
quired depth. Wells of this character are usually made in places 
where the water-bearing soil is of sand or gravel. The pipe 




Fig. 126. — Concrete cover for 
a spring. 



Fig. 127. — Concrete cistern top. 



terminates in a sand-point such as that of Fig. 128. This sand- 
point is a perforated pipe with a pointed end, that facilitates 
driving. The perforations, as shown in the point P, form a 
strainer which allows the water to enter the pipe but prevents 
the sand from filling the opening. 

In the use of driven wells, the water-bearing soil must be 
sufficiently open to allow the water to flow into the pipe as fast 
as the pump takes it away. 

Bored Wells. — In many localities the water-bearing stratum 
is of such nature as to give a ready flow of water but yet not 
sufficient to permit of the use of a sand-strainer; if, however, the 
opening is somewhat enlarged, the water will enter with sufficient 
rapidity to supply a pump. In such cases bored wells are quite 
generally used. They are made by boring a hole of the required 
size with an earth auger. These wells are made of any size up 
to 2 feet in diameter. They are often called tubular wells because 



142 



MECHANICS OF THE HOUSEHOLD 



they are lined with iron tubing or tile, to prevent the earth from 
refilling the hole. 

Cleaning of Wells. — Very few dug wells are so constructed as 
to exclude dust and washings from the ground. It is, therefore. 







ill Jii ^'^^'^ 



Fig. 128. — Driven well with a sand-point strainer. 



necessary that they be occasionally cleaned. Accumulations 
from these causes may be sufficient to hinder the entrance of the 
water to the well and thus lessen its capacity. 

Gases in Wells.- — One of the commonest gases found in wells is 
carbon dioxide (carbonic acid gas). It may be detected by 
lowering a lighted candle or lantern to the bottom. If the gas 



WATER SUPPLY 143 

is present in dangerous quantity, the flame will be extinguished. 
Death from asphyxiation due to this gas is not an uncommon 
occurrence, to persons descending into wells. Before entering a 
well, the test described above should be applied, as a precaution 
against accident. Carbon dioxide is a colorless, odorless gas 
in which a person will drown as readily as in water. 

Peculiarities of Wells.— Owing to the formation of the water- 
bearing earths, from which they receive their water, many wells 
possess marked peculiarities of behavior that often give rise to 
local reputation because of their vagaries. These characteristics 
have been classified into breathing wells, blowing wells, sucking 
wells, etc. These effects are in almost every case due to variation 
of barometric pressure. The ordinary level of the water in a 
well is governed by the variation of rainfall, melting of snow or 
the release of water by the thawing of frozen ground. It often 
occurs, however, that the head of water is markedly influenced 
by storms, when a rise of the level of the water occurs at the 
time of low barometric pressure during the storm period. This 
effect is often noticed in flowing wells. Many wells, at the ap- 
proach of storms, yield roily water to such an extent that where 
the water is normally clear it may become for a period entirely 
unfit to drink, because of the matter held in suspension. All 
of these effects are accounted for by the varying atmospheric 
pressure. At the time of high barometer, a well that ordinarily 
fiows freely will have to be pumped, the additional pressure of 
the air holding back the water to an extent representing several 
feet of head. The change of an inch in the barometric pressure 
will produce slightly more than a foot in head of water. At the 
time of storms, the barometer is sometimes abnormally low which 
will produce a corresponding rise of water in the well. At such 
time the free flow of water into a dug well, from the usual source 
of supply, will cause such a rapid flow of water through the 
passages in the earth as to carry with the water the sediment 
that produces roily water in the well. This sediment will settle 
after a while and the water will again be clear. 

Breathing Well. — Wells of this kind are most common in areas 
where the water-bearing earth is of rock formation; particularly 
in limestone areas, where caves and cavities are common. It 
sometimes happens that in the neighborhood of a well there is a 



144 MECHANICS OF THE HOUSEHOLD 

cavity in the earth of considerable volume, the only entrance to 
which is through the well and that being under usual conditions 
covered by water, a foot or more in depth. With such a forma- 
tion the conditions are right for a breathing well. At times of 
high barometer the water is depressed and the air will flow into 
the cavity through the well, when the well is said to inhale. 
This inward flow of air will continue until the air pressure in the 
cavity is equal to that of the outer air; and if the cavity is large 
and the opening small, the inward flow of air may continue for 
hours, even for days. With a fall of barometric pressure, the 
air in the cavity, being at a higher pressure than the external 
air, the air will flow outward and the well is said to exhale. 

Freezing Wells. — ^In cold climates, particularly in territory 
possessing cavernous limestone deposits, breathing wells often 
freeze in winter. When large volumes of frigid air are drawn into 
a well, the amount of heat taken from the water is sufficient to 
freeze it, and stop the supply of water. This effect is some- 
times remedied by plugging the well at the top, so that the influx 
of cold air is prevented and the water does not freeze. 

PUMPS 

Pumps for lifting and elevating water are made of both wood 
and iron in almost endless variety; but for domestic purposes 
they are of two general types — -the lift pump and the force pump 
— which include features that are common to all. The lift pump 
is intended for use in lifting water from low-head cisterns and 
wells, the depth of which is not beyond the head furnished by 
atmospheric pressure. The force pump performs the work of a 
lift pump and in addition forces the water from the outlet at a 
pressure to suit any domestic application. These pumps are 
made by manufacturers in a great variety of forms, but the essen- 
tial parts are the same in all pumps intended for a single purpose. 
The principle of operation is the same in all pumps of any type. 
The difference in mechanism of pumps intended for the same 
purpose is only in the form and arrangement of the parts. 

The Lift Pump. — The kitchen pump is an example of the lift 
pump. It is universally used for household purposes where water 
is to be raised from cisterns, etc., and is most commonly made 



WATER SUPPLY 



145 



throughout of cast iron. Fig. 129 illustrates one form, sometimes 
called the pitcher pump, because of the shght resemblance to the 
article. It frequently carries the name cistern pump from the 
fact that it very generally is used to lift water from cisterns. 

Although water may be raised 34 feet with a theoretically 
perfect pump and with a barometric pressure of 30 inches the 
actual Hmit is much lower. In use, 20 feet is probably about the 
limit and 10 feet or less is that of common practice. A pump 
that requires ''priming'' would raise water 15 feet with consider- 
able difficulty for reasons that will ap- 
pear later. In Fig. 129 is shown a sec- 
tional view of the working parts of the 
kitchen pump, the action and general 
form of which apply to any lift pump. 
The body of the pump contains a cylin- 
der, in which closely fits a piston P, con- 
taining a valve A, At the bottom of 
the cylinder is an additional valve jB. 
The piston and two valves constitute 
the working parts of the pump. The 
water is lifted through the pipe S, and is 
discharged at D. 

The action of the pump is as follows: 
With the piston at the bottom of the 
cylinders and with no water in the pump, 
the handle is forced down, which action 
raised the piston. In so doing the air 
below it is rarefied. The reduction of 
pressure due to the rarefication of the 
air allows the water to rise in the pipe aS correspondingly. After 
repeated strokes of the piston, the water reaches the valve fi, 
which raises to let it pass, but immediately closes at the end 
of the upward stroke. When the space between the piston 
and the valve B is filled with water, each descent of the piston 
forces the water through the valve A ; and when the piston is 
raised, the water is lifted out through the spout. 

The valve A is a loose piece of cast iron, surfaced on the lower 
side to make good contact with the piston. The valve B is of 
cast iron fastened to a piece of leather by a screw. The leather 

10 




Fig. 129. — Sectional 
drawing of the kitchen pump 
showing its working parts. 



146 



MECHANICS OF THE HOUSEHOLD 



makes a joint with the valve-seat and furnishes an excellent 
valve for its use. In order to keep the plunger P tight in the 
cylinder, it is surrounded with a leather gasket. Should this 
gasket become worn, as it will in time, the plunger fits loosely in 
the cylinder and the pump will lift the water with difficulty, 
because of the leakage around the gasket. Should the valve B 
leak, the water will gradually run back into the pipe S, and the 
pump when left idle will lose its ''priming.'^ The plunger and 
the valve B are the parts most likely to get out of order. If the 
gasket around the piston P is very much worn, and there is no 





Fig. 130. — Method of attaching the house 
pump to kitchen sink. 



Fig. 131. — Sectional drawing 
of the force pump showing its 
working parts. 



water in cylinder, the pump will require priming before the water 
can be raised. If the pump contains no water and is left standing 
for a considerable time, the leather parts of the valve dry out and 
shrink; when the pump is again put into use, the valves will fail 
to work properly, until the leathers are again water-soaked. 
Water is poured into the top of the pump until the cylinder is 
filled, and as soon as the leather becomes water-soaked and fills 
the cylinder, the piston will again perform its function. 

The Force Pump. — The house force pump is often used in place 
of the ordinary lift pump, when no other means is at hand for 
providing water under pressure. It furnishes a limited means 



WATER SUPPLY 



147 



^P 



for lawn sprinkling and gives some degree of fire protection in 
isolated places. It may be made a part of the kitchen sink as 
shown in Fig. 130, by use of the attachment that appears in 
detail under the sink. This type of pump may be used in small 
water-supply plants, such as that of Fig. 143; or in connection 
with small pressure tanks for the same purpose. It differs 
somewhat in construction from the lift pump, in that it has no 
valve in the piston and is provided with a check valve and an 
air chamber for generating pressure to the discharged water. 

Fig. 131 shows the essential parts of the force pump and 
furnishes a means of describing its operation. All force pumps 
possess the same parts and the operation 
described applies with equal force to all. A 
valve A is located in the bottom of the 
cylinder and the check valve B prevents the 
return of the water to the cylinder after it 
has been forced out of the pump. The ac- 
tion of the pump in raising the water is the 
same as in the lift pump but when the water 
fills the cylinder and the piston descends, 
the water is forced through the valve B and 
out at D. If the outlet pipe is slightly 
smaller than the opening in the valve B, some 
of the water will enter the air chamber C 
and compress the air. The pressure thus 
generated will immediately tend to force 
the water out and in course of ordinary 
pumping will send out a steady stream in- 
stead of the intermittent flow of the lift pump commonly used 

in small domestic water 

pump. Without the air chamber, the flow supply plants. 
from this pump will be a series of pulsa- 
tions that attain maximum force with each descent of the piston. 
Tank Pump. — The type of pump used with a water-supply 
plant will depend entirely on the amount of water that is used. 
If the supply of water to be provided is for only one or two 
people the house force pump such as that of Fig. 130 will suffice; 
but when a greater number of people are to be supplied, a force 
pump of the type shown in Fig. 132 is quite generally used. 
These pumps are made in a variety of patterns and are commonly 




Fig. 132. — Tank 



148 MECHANICS OF THE HOUSEHOLD 

termed tank pumps. The one shown in the Fig. 132 is a double- 
acting force pump in that the cyhnder receives and discharges 
water at each stroke of the piston. The air chamber is located 
at A, Directly beneath the air chamber is the valve chest in 
which are located the valves which regulate the entrance and 
discharge of the water. As used in the average domestic plant 
the cylinders are 3 or 4 inches in diameter. 

WELL PUMPS 

The pumps intended for raising water from wells are practically 
the same in construction as the house pump, except that they are 
intended to deliver a greater volume of water and sometimes to 
work under a different condition, as that of the deep well pump. 
Well pumps have, therefore, assumed certain standard forms that 
differ only in the styles of mechanism employed by different 
manufacturers. 

The one shown in Fig. 133 furnishes a good example of a 
general-purpose iron pump which may be used either as a force 
pump or a lift pump. It represents also the general construction 
of a deep-well pump, where the water must be lifted from a level, 
below that at which a lift pump will work. 

The piston and valves are enclosed in the cylinder C, placed 
below the surface of the water in the well. This cylinder also 
appears in section in the small drawing, showing the details of the 
valve. The operation of this pump is identical to that of the 
lift pump already described, but the addition of an air chamber 
gives it the necessary facility to produce a continuous flow of 
water. In order to prevent the air in the air chamber from 
escaping, the pump rod is surrounded with the necessary stuffing- 
box which is usually packed with candle wicking to assure a good 
joint. In deep wells the tube is elongated sufficiently to place 
the cylinder C below the surface of the water in the well. Such 
pumps are operated either by hand or by power. 

Wooden Pump. — The wooden pump of Fig. 134 furnishes a 
good illustration of a type that was formerly used in great 
numbers. It is an inexpensive and efficient pump made almost 
entirely of wood except the cylinder which is quite generally 
made of iron, lined with enamel. The valve and the piston 



WATER SUPPLY 



149 



with its valves are made of wood, but faced with leather to insure 
tight joints. The piston is also provided with leather packing 
to make it tight in the cylinder. The action of the pump is the 




m^m 1 




Fig. 133. — Sectional view of a well 
with an iron cylinder pump, placed for 
deep-well pumping. 



Fig. 134. — Sectional view of a 
well and wooden pump for shallow 
pumping. 



same as that already described. The wooden tube is made in 
sections joined together by taper joints that are driven into place. 
The piece at the side of the pump is provided to drain the water 
from above the piston, as a precaution against freezing during 
extremely cold weather. The rod, when raised, opens an orifice 



150 MECHANICS OF THE HOUSEHOLD 

that leads to the inside of the pump and permits the water to 
drain into the well. 

Pumps for Driven Wells. — The method of constructing driven 
wells — that of driving a pipe into the earth to the water-bearing 
stratum of sand or gravel — requires a special end to prevent the 
pump tube from becoming stopped. In order that the fine 
material may not enter and fill the lower end of the tube, a 
sand-point is used, such as that shown in Fig. 128. It is made of 
perforated brass tubing and provided with a sharpened end to 
facilitate driving. The perforations act as a strainer that keeps 
out all but the fine particles which will pass the pump valves. 
Sand-points are made with strainers of various degrees of fineness 
to suit the different conditions of soils. These strainers may 
in the course of time become filled w^ith particles of the soil that 
lodge in the perforations and the outside become so encrusted as 
to prevent the entrance of the water. In such case, the pipe 
must be pulled out of the ground and the point replaced by a new 
one. In Fig. 128 is shown a driven well with the sand-point in 
the water-bearing stratum. If the small particles of earth clog 
the strainer the pump will ^^work hard^^ and yield only a portion 
of the water the soil is capable of giving when the strainer is 
clear. 

Deep-well Pumps.— The principle of operation as described 
in the lift pump takes advantage of the atmospheric pressure to 
lift the water above the first valve. The limiting distance to 
which water can be lifted by the atmospheric pressure will depend 
on the altitude and the atmospheric pressure. With the normal 
atmospheric pressure at sea level, water can be lifted, theoretic- 
ally, 34 feet, but in practice the limiting value is never even 
approximated. The pump is usually placed within 10 or 12 feet 
of the water and 20 feet is about the limit of distance. The 
reason for this is because of the impossibility of keeping the joints 
tight in the valve and tubing. 

Where water is to be raised from a deep well, the cylinder with 
its piston is placed near the water and the tube and rod, as that 
of Fig. 133, connects the cylinder with the pump stock. After 
the water has passed the valve in the piston, it may be readily 
lifted to the pump stock. In this way water is raised from wells 
of great depth. 



WATER SUPPLY 



151 



Tubular-well Cylinders. — Tubular wells that are cased with 

iron pipe are provided with a special type of pump ^ 

cylinder that admits of deep-well operation. The 
casing of the well being in place, the cylinder shown 
in Fig. 135 is forced down the casing to its proper 
place, the spring S holding it in place until it is firmly 
secured. A special seating tool is now lowered into 
the casing and attaches at T to the coupling; as the 
tool is turned, rubber packing R is expanded, locking 
the cylinder firmly to the casing. This makes a com- 
plete pump cylinder, which with the piston P in place 
is operated as any other pump. 

Chain Pumps. — In shallow wells and other sources 
of supply, where water is to be lifted only a short 
distance, chain pumps have been used to a great ex- 
tent, because of their quick action. This pump, as 
shown in Fig. 136, elevates the water by an endless 
chain being drawn through the tube, the lower end 
of which is below the surface of the water. The chain 
is provided at intervals with discs or rubber or iron, 
that fit the bore of the tube and form pistons which 
elevate the water as they ascend. The chain passes 
around a wheel in the upper part of the box and is 

worked by the crank. Chain pumps are not 
usually employed to elevate water a greater 
height than 20 feet. They are not efficient 
pumps and are not sanitary because of the 
opportunity they give for admitting pollut- 
ing material to the well. Their one advant- 
age is that of quick action in elevating water 
short distances. 

RAIN-WATER CISTERNS 

Cisterns for the storage of rain water have 
been used from the time immemorial and are 
constructed in a great variety of forms. For 
household use they are often made in the form 
of wooden or metal tanks, either elevated or 
placed in the basement; the greater number, however, are of 
the underground variety made of brick or concrete. 



Fig. 135. 




Fig. 136.— Chain 
pump often used in 
shallow wells. 



152 MECHANICS OF THE HOUSEHOLD 

Wooden cisterns are made by manufacturers in different sizes 
and shipped to the user ^^ knocked down; '' that is, they are taken 
apart and the staves, bottom and hoops are shipped, packed in 
small space to save space in transportation. Under some condi- 
tions they give good service but are apt to leak at times and 
require attention on that account. In damp basements they 
give out the disagreeable odor of damp wood. 

Tanks made of galvanized iron are much used as cisterns for 
temporary use. They are inexpensive and give good service 
but are short-lived. Possibility of leakage is their greatest dis- 
advantage. Underground cisterns are built either in the base- 
ment or outside the house. They are quite generally made jug- 
shaped, but are often constructed of concrete in square and 
rectangular form. When built of brick the walls are often made 
of a single course, but walls made of two courses of brick are 
considered better practice. The walls and floor are made water- 
tight by plastering with an inch or more of cement mortar. 

When cisterns are made of concrete, the floor should be put 
in 6 inches in depth and as soon after as possible the walls are put 
up. In good construction the walls are 8 inches in thickness of 
concrete, made of 1 part good Portland cement, 2 parts clean 
sand and 4 parts crushed stone. If the cistern is square or 
rectangular in form the walls should be reinforced with woven 
wire or steel rods, to prevent cracking. 

The curb of the cistern should extend above the surface of the 
ground sufficiently to prevent surface water from entering, and 
the top should be covered with a wood-lined sheet-metal cover 
to prevent freezing. 

Filters. — Unfiltered cistern water is not, as a rule, fit for drink- 
ing purposes because of pollution from dust and impurities 
washed from the roof, but for bathing and laundry work filtered 
rain water is greatly to be desired. 

As rain water comes from the roofs of buildings, there is 
washed into the cistern a considerable quantity of dust, leaves, 
bird droppings and other polluting materials which contaminate 
and discolor the water. This foreign matter is not injurious 
for the purposes intended, but to render the water clear it should 
be filtered before using. 

Filters for cisterns are quite generally made of soft brick laid in 



WATER SUPPLY 



153 



cement mortar, the face of the brick being left uncovered. Fig. 
137 illustrates a simple and efficient form of filter made of a 
single course of brick. A space one-fourth to one-third of the 
volume of the cistern is left for the filtered water. The opening 
at the top of the wall must be large enough to admit a man, for 
some sediment will collect even in the filtered water and the filter 
must be occasionally cleaned. 



Capacity-385 Cu. Ft, 
or 90 Barrels of ZlVz 
Gallons each 




Capacity-400Cu.Ft. 
or 90 Barrels of 31 H 
Gallons each 



, 137. — Cross-section of a brick curbed 
cistern with a brick filter wall. 



-Cross-section of a con- 
crete cistern with a brick dome filter. 



The filter shown in Fig. 138 is dome-shaped and built of brick. 
The water is pumped from inside the filter and the suction of 
pumping filters the water as it is used. In this case the filtering 
action is accelerated by reason of the reduced, pressure inside the 
filter as the water is pumped. The chief disadvantage in this 
form of filter is the small area exposed for the filtering action and 
the relatively greater amount of work required for pumping the 
water, due to the partial vacuum formed as the water is pumped. 

The cistern in Fig. 139 is provided with a catch basin which 
acts as a strainer for removing leaves, etc., that would stain the 
water. It is made in the form of a concrete basin and partly 
filled with gravel. The filter in this case is formed by a depres- 
sion in the cistern floor. A section of tile is placed on the floor, 



154 



MECHANICS OF THE HOUSEHOLD 



and around it is filled the filtering material of gravel and sand. 
Filters of this kind are often filled with charcoal or other materials 
that are expected to purify the water. They are usually in- 
efficient because their value as absorbers of polluting agents is 
short-lived and unless the materials are frequently renewed they 
are valueless and sometimes a detriment to rapid filtration. 




Fig. 139. — Cross-section of a concrete cistern, containing a sand filter. 



THE HYDRAULIC RAM 

In places where its use is possible, the hydraulic ram is a most 
convenient and inexpensive means of mechanical water supply. 
It is simple in construction, requires very little attention and 
its cost of operation is only the labor necessary to keep it in 
repair. Whenever a sufficient supply of water will admit of a 
fall of a few feet, the hydraulic ram may be used as a pump for 
forcing the water to a distant elevated point, where it may be 
utilized for all domestic purposes. The water may be used 
directly from the ram or stored in an elevated tank as a reserve 
supply; or accumulated in a pressure tank, where additional 
pressure is required. 

The hydraulic ram has been used since 1796, when it was 
invented by Joseph de Montgolfier. The principle of its opera- 



WATER SUPPLY 



155 



tion is that of the utiHzation of the energy of flowing water. The 
running water is made to give up a portion of its momentum to 
elevate a part of the water, and transport it to a considerable 
distance. If the source of supply and the fall is sufficient, almost 
any amount may be elevated and carried to a great distance. 
Large rams are sometimes used as a means of water supply for 
small towns. In the use of the double-acting ram, one source 
of water may be used to operate the ram and water from an 
entirely different source may be delivered. It sometimes 
happens that a muddy stream and a clear spring are so located, 
that the water of the stream can be utilized to furnish the energy 
for conveying the spring water to a point where it is desired for 
use. This is accomplished by the double-acting ram in a most 
efficient manner. 

Single-acting Hydraulic Ram. — Fig. 140 represents the instal- 
lation of a single-acting hydraulic ram, placed to take water from 



1 




1 


1 


,V .'^ 


% 

fe 


;^,:.^%j^^^ 


^^ 




M 






W^^^^ 


"^^Pl 



Fig. 140. — Hydraulic ram driven by the water from a spring. 



a spring E, and deliver it to an elevated tank at the house on the 
hill. 

In case the ram must be located at a considerable distance 
from the spring in order to attain the required fall, a standpipe 
D — slightly larger than the supply pipe — is used to take ad- 
vantage of the full force of the water. In long pipes, the friction 
of the flowing water absorbs a considerable amount of the energy 
of flow and a standpipe, located as indicated at Z), in the picture, 
will assure the full force of the flowing water in the ram. 

The ram is commonly placed in an underground pit as protec- 
tion from freezing during cold weather, and a drain from the 
bottom of the pit conducts the waste water away. The supply 



156 



MECHANICS OF THE HOUSEHOLD 



pipe or drive pipe B and delivery pipe C are buried underground 
below the frost line as a protection from freezing. 

In Fig. 141 a sectional view of the ram shows all of the working 
parts. The air chamber G is shown partly filled with water; the 
impetus valve D is that part of the ram which checks the flow of 
the running water and forces a part of it through the valve E, at 
the bottom of the air chamber. 

When inactive the valve D stands open and as the water enters 
from the pipe A, it flows through the valve to the waste pipe but 
as soon as the full force of the water bears on the valve it will 
suddenly close. This sudden stop of the flowing water will lift 




Fig 



Delivery 
Pipe 

141. — Cross-section of a single-acting hydraulic ram. 



the valve E, and the energy of flow, due to its sudden stopping, 
will force some of the water into the chamber G. As this action 
occurs the upward pressure against the valve D is released and 
it reopens but immediately closes again as the water begins to 
flow. This process is kept up, each closure of the valve sending 
a little water into the air chamber. As the water gradually fills 
the air chamber, it is subjected to the same action as was de- 
scribed in the pressure tank, the air above the surface being com- 
pressed and the pressure developed in the space G forces the water 
out through the delivery pipe where it attains a force that is a 
factor of the height of the original fall. 

The air in the chamber G, is subject to the same conditions 



WATER SUPPLY 



157 



of loss as that of the pressure tank, and to be assured of a supply- 
to give pressure to the water, some air must be carried into the 
chamber with the water. For this purpose the valve F pro- 
vided. After the chamber is partially filled, there occurs a re- 
action in the flow of water at each closure of the valve, which 
causes a little air to be drawn in through the valve F with each 
impulse. This air bubbles up through the water and enters 
the chamber where it assures an elastic cushion for closing the 
valve E, 

The flow of water from the supply pipe is regulated at fl" by a 
nut on the stem of the impetus valve which permits its regulation. 
Closing the valve slightly causes a less supply of water to be 
delivered; opening the valve wider gives a greater supply. 




Fig. 142.= — Sectional view of a double-acting hydraulic ram. 

The Double-acting Hydraulic Ram. — The diagram of Fig. 142 
illustrates the working principle of the double-acting hydraulic 
ram mentioned above; where the water from a muddy stream is 
used to drive the ram and that from a separate source, as a spring 
is delivered. 

The construction of the double-acting ram is similar to the 
single-acting ram, but a separate pipe aS discharges spring water 
directly below the valve which acts just asthough it had entered 
at the drive pipe. The ram in this case is receiving water from 
the drive pipe D, which operates the valve and furnishes power 
for elevating the spring water. The spring water enters the 
ram through the pipe aS, to keep the space T filled, directly under 
the valve. The water which enters the air chamber is, therefore, 
only that from the spring. 

A standpipe is arranged as shown in the figure, with a check 



158 MECHANICS OF THE HOUSEHOLD 

valve to prevent the water in the ram from being forced back 
into the spring water pipe after entering the ram. 

DOMESTIC WATER-SUPPLY PLANTS 

Until recent years, no thought was given to private water- 
supply plants, in any except the more pretentious residences. 
It was formerly supposed that the cost of machinery and instal- 
lation of such plants prohibited the use of a water system in the 
average home. As an item of expense in building, a satisfactory 
water-supply system may be installed at a lower cost than is 
paid for plumbing and bathroom fixtures. 

In recent years much attention has been given to the design 
of small water-supply plants for isolated homes, such as are 
required for suburban and rural dwellings, with the result that 
the necessary apparatus to suit any conditions may be obtained 
of any enterprising dealer. 

The degree of completeness with which the plant is to be 
arranged will depend on the funds to be expended, but in the most 
modest dwelling some form of water-supply plant is possible. 
Where opportunity is given to make the plant complete, its 
appointments of construction may be elaborated to almost any 
extent. A suburban or country residence may be made as 
perfect in point of toilet, kitchen and laundry conveniences, as 
where city water and sewer service are available. The water- 
supply plant may be operated by hand or by power, and if so 
desired may be made completely automatic in action. 

Gravity Water-supply Plant. — In point of simplic'ty, the plant 
shown in Fig. 143 represents a water system that answers every 
purpose of a cottage and yet is only an elevated tank for storage 
of water, combined with a house force pump. The tank in this 
case may be made of wood or metal and is open at the top. The 
water is sent into the tank by the pump, and gravity furnishes 
the force for carrying it to the fixtures in the kitchen and 
bathroom. 

In using a tank of the kind shown in the drawing, provision 
should be made for the possibility of leakage. This is arranged 
for by having the tank set in a shallow pan, so constructed that 
in case of accident the water may be carried away without doing 



WATER SUPPLY 



159 



damage. This type of plant is not usually employed in cold 
climates, unless some provision is made to prevent the water in 
the tank from freezing. Tanks of this kind are sometimes used 
in cold climates but a much more desirable plant for the purpose 
is described below. In Fig. 143 the water from the cistern W is 
raised by the pump P, which also forces it into the tank above 
the kitchen. The gravitational force given the water, because 




Fig. 143. — Sectional view of a cottage containing a simple gravity water-supply 

plant. 

of its elevated position is all that is necessary to carry the water 
to the fixtures in the bathroom and kitchen sink. As shown in 
the drawing, it furnishes a complete water system that will 
perform all of the requirements of water distribution for a small 
family. 

The pipes from the range boiler are attached to the water 
heater, which forms a part of the kitchen range as explained on 
pages 116 to 120. It receives the supply of cold water directly 
from the tank through the pipe marked C, and the hot water 
from the range boiler is supplied through the pipe H. Cold water 
is also taken from the tank directly to each of the cold-water taps. 



160 MECHANICS OF THE HOUSEHOLD 

The pump P is a house pump, such as is shown in Fig. 130. 
It is a small force pump, designed to suit the conditions of 
domestic use and is made to send water into the sink or into the 
supply tank as desired. 

Pressure -tank System of Water Supply. — The water-supply 
plant shown in Fig. 144 is another simple construction, somewhat 
more elaborate than the last, so arranged that the danger of 
freezing is practically eliminated. This is a simple pressure- 
tank system in which a tightly built metal water tank takes the 
place of the elevated tank of the previous figure, and a tank 
pump is used for lifting and giving pressure to the water. It is 
a more complete plant than the first and intended to accom- 
modate a larger dwelling. The drawing shows all of the fixtures 
and connecting pipes that are required in the average home. 
It shows all of the appliances for connecting the pressure tank 
and range boiler with the wash trays in the basement, with all 
of the fixtures in the bathroom and with the fixtures in the 
kitchen sink. The range boiler is the same as those previously 
described and connected to the heater in an identical manner. 

The original source of supply in this case is a cistern, sunk 
below the basement floor. The water is lifted from the cistern 
by the pump and forced into the pressure tank through a pipe 
near the bottom where it furnishes the supply for the house. 

The pressure tank may be of any size to suit the requirements 
of the house and may be placed in either a vertical or horizontal 
position. It is sometimes galvanized, as a precaution against 
rust, but this is not a necessary requirement. The pipe which 
conveys the water from the pump connects with the tank near 
the bottom. As the water enters, the contained air above its 
surface is compressed into smaller and smaller space. The 
pressure that is developed by the compressed air furnishes 
the force by which the water is driven out of the tank and 
through the distributing pipes to the various parts of the 
system. 

If the air in the tank when empty is compressed to one-half 
its original volume, then the gage pressure will be about 15 
pounds to the square inch; if the air is compressed to one-third 
its original volume, that is, when the tank is two-thirds full of 
water, the gage pressure will be about 30 pounds to the square 



WATER SUPPLY 



161 



inch, which is enough to supply water at any point of a two-story 
building with ample force. By pumping more water into the 
tank, a pressure of 50 or 60 pounds may be obtained without 
difficulty; but 40 pounds is generally sufficient for all the demands 
of a house plant. This is an application of the Boyles law which 
as stated in text books of physics is: ^^The temperature remaining 




Fig. 144. — The pressure-tank system of water supply as it appears in a dwelling. 



the same, the pressure on confined gas varies inversely as its 
volume. '^ As the volume of such a confined body of gas is made 
smaller, the pressure increases in like ratio. The desired pres- 
sures are easily attained with a hand force pump such as is shown 
in the drawing. 

The gage-glass G on the side of the tank is intended to show 
11 



162 



MECHANICS OF THE HOUSEHOLD 



the height of the water in the tank at any time, and the pressure 
gage attached to the supply pipe shows the amount of pressure 
sustained by the water. 

The Pressure Tank. — The water leaves the tank by a pipe 
attached near the bottom and branches to supply each fixture, 
to which the water is to be conducted. In the drawing, the pipe 
may be traced from the point where it leaves the tank to the vari- 
ous fixtures. The cold-water pipe terminates at the range boiler, 
for at that point the hot- water system begins. The range boiler 
is connected by two pipes to the water heater in the kitchen 
range. The water heater is a part of the fire-box of the kitchen 

range and so long as the fire is kept 
burning, water is heated and stored 
in the range boiler. Where the 
house is furnace-heated, the furnace 
fire is sometimes utilized for heat- 
ing the water by use of a coil of pipe 
above the fire and which may take 
the place of the range heater. Vari- 
ous other means are also employed 
for heating the water as described 
under range boilers. In Fig. 145 is 
shown a nearer view of a pressure 
tank with the pump attached. The 
pump is in this case identical in its 
Fig. 145.— The pressure tank action to the one shown in Fig. 132, 
complete, wtih the pump and ^^^ differs slightly in mechanical de- 
gages as used for domestic water . n-n i • i 

supply. Sign, ihe drawing shows the gage- 

glass G, for indicating the height of 
water; the pressure gage P, which indicates the pressure to 
which the water is subjected; the attachment of the supply 
pipe S, and the delivery pipe D, The water tap T is provided 
to draw off the water when the tank is to be emptied. 

In operation, the air in the pressure tank furnishes the force 
which sends the water through the pipes to the various points, 
and forces it through the taps at the desired rate. If for any 
reason the air in the tank escapes, the propelling force is de- 
stroyed. This may occur by reason of absorption of the air by 
the water, due to the pressure to which it is subjected; or to 




WATER SUPPLY 



163 



small air leaks that may develop in the joints, which allow the 
air to escape. To overcome the possibility of these occurrences, 
arrangement is made whereby air may be pumped into the tank 
by the same pump as that which supplies the water. In this 
way, the air is introduced with the water, which bubbles up 
through it to the surface. If at any time the pressure in the tank 
is lost, it may be replaced by pumping air alone into the tank. 

Power Water-supply Plants. — Where the pump is expected 
to furnish water to any considerable amount beyond that for 
household use, it is desirable that the plant be power-driven. 
If the work of watering stock, lawn sprinkling, etc., is intended, 




Fig. 146. — Tank pump operated by a small gasoline engine. 

the tank and pump must be enlarged to suit the desired amount 
of water, and a gasoline engine, windmill or electric motor will 
be used for power. Where local conditions will permit, a 
hydraulic ram may be substituted for the pump and the pressure 
tank used for additional pressure and storage. 

Fig. 146 shows a plant in which the pump is driven by a 
gasoline engine. In the figure, the engine E is shown connected 
by a belt to a speed-reducing device or ^^jack,'^ marked J. The 
object of this machine is to reduce the speed of rotation and 
charge it to the required motion for operating the pump. The 



164 



MECHANICS OF THE HOUSEHOLD 



jack is connected to the pump by a rod attached to a large gear, 
so as to produce the desired crank motion; and the opposite end 
of the rod is attached to the pump handle. The rod may be 
detached at any time and the pump worked by hand. 

Electric Power Water Supply. — Fig. 147 shows another type 
of power plant in which an electric motor operates the pump. 
In this style of plant, the pulley on the electric motor M is 
connected by a belt to the large wheel TF, from which the crank 
motion is secured for driving the pump P. This machine is 
provided with an automatic starting and stopping device, which 

automatically controls the supply 
of water in the system. Whenever 
the pressure in the tank falls to a 
certain point, the change of pressure 
produced on the diaphram valve A 
starts the motor, and the pump sends 
water into the tank until the pressure 
in the tank again reaches the amount 
for which the valve is set, at which 
time the valve disconnects the elec- 
tric contact to the motor and the 
pump stops working. 

Wind -power Water Supply. — In 
Fig. 148 is shown a larger and more 
complete plant than the former, in 
which a windmill furnishes the power 
for pumping and a large under- 
ground tank is utilized for the main 
Fig. 147. — Pressure tank supplied supply of Water. The tank marked, 
by an electrically driven pump, ^^jj ^^^^^ Pressure Tank, in this 

case is so placed that the end is exposed in the well curb, where 
the height of the water may be observed at any time. The 
pump is operated as any other of its kind, but is provided with 
an automatic pressure cylinder, which controls the operation of 
the mill through the rise and fall of the water in the tank. At 
any time the water in the tank falls to a certain point, the 
pump is thrown into gear by the pressure cylinder, and the 
water is pumped into the tank until a definite height is reached; 
at this point the pump is autom^atically thrown out of gear and 




WATER SUPPLY 



165 



remains inactive until an additional supply of water is required. 
The plant is therefore automatic in its action and requires only 
that the mill be kept oiled and in running order. 

As shown in the drawing, the large tank receives its supply of 
water from the well and aside from providing a reserve supply 
furnishes power for pumping cistern water. The water from 
the large tank is piped into the house for use as required, and from 




Hydrant 



^^^^^^^^^^^^^5^^^ 




Fig. 148. — This diagram shows the arrangement of domestic water-supply- 
apparatus, in which a windmill furnishes the pressure necessary for operating 
the entire plant. 

the same pipe is taken a hydrant for lawn sprinkhng; in addition, 
this water is piped to the barn where it is used for watering stock. 
A branch of the same pipe is intended to operate a water lift, 
which in turn furnishes the house with soft water from the rain- 
water cistern for bathing, laundry, and kitchen purposes. 

The Water Lift. — The water lift is a combined water engine 
and pump, the motive power for which is the pressure from the 



166 



MECHANICS OF THE HOUSEHOLD 



well-water tank. The soft water, pumped by the water lift, 
is stored in the smaller pressure tank marked Soft Water Pressure 
Tank in the drawing, and furnishes a supply for the purposes 
mentioned. The water lift is so constructed that when the 
pressure in the soft-water tank equals the pressure in the well- 
water tank, the lift will stop working and will not start again 
until water has been drawn from the taps. Whenever water is 
drawn from any part of the system, the pressure will be reduced 
and the lift will immediately begin pumping more water and will 
continue until the pressure of the two tanks are the same. The 
system is entirely automatic, each part depending on the power 



ADJUSTABLE 
REGULATOR 



DISCHARGE; 




SUCTION- 



■llr 

Fig. 149.— The water lift. 



WASTE 



originally supplied by the windmill. The plant could be just as 
successfully operated by substituting a gasoline engine or other 
source of power for the windmill. The machinery for such a 
plant is not at all complicated neither is it difficult to manage, 
yet it is complete in every particular and furnishes an almost 
ideal arrangement for a country or suburban home. 

In order to be assured of a supply of water over periods of 
atmospheric quiet, the well-water tank must be sufficiently 
large to supply water for 3 or 4 days; but in case of emergency 
water may be pumped by hand. 

A nearer view of the water lift is shown in Fig. 149. In the 



WATER SUPPLY 



167 



figure, the right-hand cyHnder with its valve V is the water 
engine which furnishes the power for operating the pump, en- 
closed in the left-hand cylinder. The water pressure of the 
main supply furnishes the energy which drives the engine, the 
piston rod of which is attached to the pump piston. The engine 
receives its supply of water through the pipe marked Inlet and 




1 Air Chamber Nut 

2 Brass Tube for Air 
Chamber 

3 Air Chamber 

4 Brass Cock 

5 Cap Screw 

6 Leather Washer 

7 Handle Pin 

8 Pitman 

9 Handle 

10 Brass Covered 
Piston Rod 

11 Fulcrum 

12 Fulcrum Pin 

13 Brass Stu.ffijig ifut 




14 Cap 

15 Fulcrum Ring 

16 Fulcrum Ring 
Pin 

17 Plunger 

18 Cylinder 

19 Cap Screw 

20 Lower Valve 

21 Brass Valve 
Seat 

22 Base 

123 Bottom Brass 

Ferrule 
24 Bottom Nut 



Fig. 150. — The terms by which the parts of a force pump are designated. 

the waste water is discharged to the sewer by the waste pipe on 
the opposite side of the cylinder. The operation of the lift is gov- 
erned by an automatic regulator which so controls the engine 
that it starts pumping whenever the pressure in the system falls 
to a certain point. The regulator marked Adjustable Regulator 
in the drawing may be adjusted to suit the water pressure desired 
in the distributing system. 



CHAPTER VIII 
SEWAGE DISPOSAL 

The disposal of sewage, in a convenient and sanitary manner . 
is a problem of serious importance in the equipment of isolated 
dwellings with modern household conveniences. The manner of 
heating, lighting and of water supply are questions of selection 
among a number of established systems, but the problem of sew- 
age disposal must in a great measure be determined by local 
conditions. Unless the natural surroundings are such as will 
permit sewage to be emptied directly into a stream of considerable 
volume, the problem of its safe disposal becomes one of serious 
importance. 

Sewage is understood to mean the fluid waste from the kitchen, 
toilet and laundry and has nothing whatever to do with garbage. 
Sewage disposal has to do with conducting away the house 
waste and disposing of it in a sanitary manner. Sewage disposal 
does not necessarily have anything to do with sewage purifica- 
tion; although a sewage disposal plant may be so constructed as 
to discharge a purified effiuent, it usually is understood to. have 
to do alone with its disposal in a manner that does not offend 
the aesthetic sense. A simple sewage plant is anything that 
will take the sewage away from the house in such a way as to 
produce no unsightly accumulations that will decay and produce 
offensive odors. 

A sewage purification plant is one in which the raw sewage from 
the house drain is first liquefied, after which the liquid is passed 
into a filter where it undergoes a process of bacterial disintegra- 
tion and the organic matter reduced to the inorganic state, where 
no further change is possible. The water which flows from such 
a filter is clear and sparkling, and is often taken for spring water. 
The degree of purification given to the sewage will depend on 
the style of filter and the length of time necessary for the water 
to pass through it. 

168 



SEWAGE DISPOSAL 169 

Sewage is composed of organic matter in a fluid or part fluid 
condition, contained in a large volume of water. It is not usually 
the dark, heavy, foul-smelling fluid that is imagined by many, 
but a turbid liquid possessing only a few of the quahties usually 
ascribed to sewage. Under favorable conditions practically 
all of the organic matter will be readily dissolved and the sewage 
will become entirely liquid. 

As a liquid, the raw sewage is in the most favorable condition 
for rapid decay and if left standing in the air it soon develops 
properties that render it highly objectionable. 

The decay of all organic matter is a process of disintegration 
that ultimately ends in the elements from which it came. In the 
disposal of sewage, the aim is to permit this disintegration to 
take place under conditions that will be least offensive to the 
aesthetic sensibilities, and in some cases to render it free from 
harmful properties should there be present the bacteria of com- 
municable disease. 

The successful disposal of sewage from cities is accomplished 
under a great variety of conditions. It is much easier to arrange 
for sewage purification on a large scale than in a small way. 
The reason for this is that in the care of a city the sewage-disposal 
plant is under the supervision of a competent person, whose 
business it is to see that the conditions are kept at the highest 
efficiency. Private plants are left almost entirely without care, 
until they fail from causes that are usually preventable. Sewage 
may be successfully purified under a great many conditions, 
but no type of plant has as yet proven itself successful that does 
not receive intelligent attention. 

The most successful of small sewage disposal plant is the 
septic tank system alone or in connection, with an adequate 
form of bacterial filter. Cesspools are not to be countenanced 
by people of intelligence. The cesspool has been so universally 
condemned by authorities on sanitation, that all intelligent 
people look upon it as a thing filthy beyond description. Al- 
though the septic tank is little more than an improved cess- 
pool, the condition under which it acts is entirely different 
from that which takes place in the latter and with care 
and watchfulness, it may be made to work to a degree of 
perfection that is surprising. The one great cause of the 



170 MECHANICS OF THE HOUSEHOLD 

failure of small sewage-disposal plants is the lack of proper 
care. 

The process of sewage purification as now practised in the 
most successful plants is largely mechanical, but bacterial ac- 
tion plays a part of great importance in the completion of 
the process. It consists of two stages: the tank treatment, 
in which the sewage is liquefied; and the process of filtration 
where the liquefied sewage — commonly called the effluent — 
from the septic tank undergoes a process of filtration and 
bacterial purification. 

The Septic Tank. — The septic tank alone, as used for sewage 
disposal, is often termed a sewage purifying plant, when in reality 
it is only intended to change the sewage into a form in which it can 
be readily carried away. The word septic means putrifying, 
and when applied to sewage disposal it furnishes a convenient 
term but has nothing to do with purification. The septic tank 
furnishes only the first stage of the purifying process, and al- 
though its effluent may be clear and possess little odor, it is 
nevertheless unpurified. The septic tank discharges an effluent 
of more or less completely digested sewage, instead, as in the 
cesspool, of permitting it to remain a constantly festering mass, 
to be slowly absorbed by the earth. 

The sewage is first collected in a tank of sufflcient size to con- 
tain the discharge from the house for 24 hours. In the process 
of digestion which the sewage undergoes while in the tank, it is 
rendered almost entirely liquid ; at the same time it is acted upon 
by the bacteria that are developed, and that tend to reduce the 
sewage to its elemental form. The effluent liquid which passes out 
of the tank is almost colorless and possesses relatively little odor. 

The tendency of the change which takes place in the tank is 
to nitrify the organic matter but under ordinary conditions the 
action is not fully complete. The effluent sometimes undergoes 
but little change except to be reduced to a liquid. If the effluent 
is now allowed to flow into a ditch where it will stand in pools, 
further putrification will take place with its resulting annoyance. 
In case the septic tank is to be used alone, the effluent should be 
conducted to a stream for final disposal. A septic tank must be 
built to accommodate a certain number of people and of sufflcient 
size to take care of the entering sewage. The action which goes 



SEWAGE DISPOSAL 171 

on in the tank will render the contents almost entirely fluid, and 
under good conditions the sewage will be completely digested. 
When working properly, a thick scum will form on the surface, 
through which filters the gases that are liberated in the process 
of disintegration. The formation of the scum is an indication 
that the filter is doing its best work. Should the tank be re- 
quired to take care of more sewage than it can conveniently 
handle, the scum will not form and the effluent will be turbid 
because of the undigested matter. 

The change that takes place in the sewage while it remains in 
the tank is first that of being liquefied and then disintegrated by 
bacterial action. That such a change does take place is evi- 
denced by the residue that is- found in the tank in the process of 
cleaning. This is a black granular substance, composed mostly 
of humus and commonly known as sludge. The amount of 
accumulated sludge is relatively small, and the operation of clean- 
ing is not necessary more than twice a year and is not the dis- 
agreeable task one might suppose. 

The Septic Tank With a Sand-bed Filter. — In places where 
the use of the septic tank alone is not possible, it sometimes 
happens that the natural conditions are such as will permit the 
effluent to be drained directly into the soil. With such a con- 
dition, the effluent goes into a filter bed composed of gravel or 
other loose material, where it undergoes still further bacterial 
action and if the process is complete, the water which comes 
from the filter bed is clear and odorless. Under good conditions 
it is clear sparkling water and contains but a smaU amount of 
impurities. 

Septic tanks are made in many forms but that iUustrated in 
Figs. 151 and 152 is commonly used. In Fig. 151 the tank is 
shown in position to receive the sewage from the house drain, 
where it is to undergo the first treatment and then to be con- 
ducted to a filter bed made of porous tile, set in loose soil. The 
tank is shown in detail in Fig. 152. It is a cemented brick 
cistern with an opening to the surface that contains a double 
cover as a protection during cold weather. A brick partition 
divides the tank into spaces G and //, that contain volumes that 
are to each other as 1 to 2. The tank is of such size as will hold 
a volume of sewage equal to 24 hours' use; that is, it is expected 



172 



MECHANICS OF THE HOUSEHOLD 



that any portion of sewage will remain in the tank for that length 
of time. The sewage enters at A, in such a way as will give the 
least disturbance of the liquid of the tank. An opening C allows 
the liquid to pass from H into G, where any additional sewage 
entering i? will displace an equal amount in G, which will pass 
out at B to the filter bed. The partition D is high enough so 
that the scum that forms on the surface will not pass directly 
into the space G, The entrance and exit pipes are made of 
vitrified sewer tile with the openings below the surface. 




Fig. 151. — Sectional view of a septic tank, connected with a sand-bed filter; for 
the disposal of sewage from a residence. 

As the sewage enters the tank A, a considerable portion will 
sink to the bottom, while some will float to the top where a thick 
scum will gather. By far the greatest portion of solids will be 
readily dissolved in the water and the remainder will be still 
further reduced to liquid form by bacterial solution. The process 
of disintegration that goes on evolves a considerable amount of 
carbon dioxide and ammonia which filters through the scum. 
The process that now goes on in the tank is that of liquefying the 
organic matter and changing it from organic to the inorganic 
state. 

The bacteriologist recognizes in the process of sewage disin- 
tegration the work of two classes of bacteria, the aerobic or those 



SEWAGE DISPOSAL 



173 



bacteria that work by reason of air and do their work only in its 
presence and the anaerobic or those that work in the absence of 
air. In the action of the sewage-disposal plant both kinds of 
bacteria are at work. If, in the final stage where the sewage 
passes into the filter, air can be carried into the earth the action 
will be hastened. 

It is evident that, since the sewage entering the tank is 
almost entirely dissolved, under ideal action this system would 
give very little trouble, but actually as the sewage enters the 




Fig. 152. — Section of the septic tank in Fig. 151 showing details of construction. 

tank the disturbance caused by the incoming water forces some 
of the undigested matter into the outlet and being carried into 
the filter bed it will be deposited at the first opportunity. This 
will cause the filter bed to fill up with undigested sewage at the 
point nearest the entrance, and in course of time it will stop the 
pipe because of this accumulation. 

To avoid such an occurrence, tanks have been built in which an 
automatic siphon discharges the effluent whenever a certain 
quantity has collected. Such a tank is shown in Fig. 153. With 
this arrangement, the sewage enters the first tank at -4, and passes 



174 



MECHANICS OF THE HOUSEHOLD 



into the second tank at B. At S is shown an automatic siphon, 
so made that when the effluent has collected to the height of the 
water line, the siphon automatically discharges the contents of 
the tank. This is known as a dosage tank because periodically 
a dose of the effluent is discharged into the filter bed. The 
volume discharged is sufficient to fill the greater portion of the 
bed, and force out the air in the loose soil. As the water filters 
from the bed the air is drawn in to take its place and gives the 
bacteria which work in the presence of air an opportunity to 
do their work. The work done by this filter bed is first to filter 
out any suspended matter carried in the effluent which will lodge 
on the surface of the filter material and then to undergo the slow 




Fig. 153. — Sectional view of a two-chamber septic tank with a dosage siphon. 

process of integration, and to permit the oxidation of the dis- 
solved sewage. If this matter is deposited faster than it dis- 
integrates then the filter will fill up and finally refuse to work. 

The Septic Tank and Anaerobic Filter.^ — In places where the 
use of the simple septic tank is not possible and where the char- 
acter of the soil will not permit of a natural sand-bed filter, an 
anaerobic filter may be constructed through which to pass the 
effluent from the septic tank. 

The anaerobic filter is one in which anaerobic bacterial action 
is given opportunity to reduce the organic matter in the sewage 
to its elemental condition. The filter may be constructed in any 
form that will permit the process of filtration to be carried out 
in a Avay that will afford good anaerobic action. The extent to 



SEWAGE DISPOSAL 



175 



which the purification is to be carried will determine the form and 
size of the filter. 

In Fig. 154 is shown such a plant, where a combined septic tank 
and anaerobic filter discharges its effluent into a filter ditch in 
which the purifying process is continued through a bed of gravel 
of any desired length. The figure illustrates a plant that was 
designed for a country residence. The septic tank and anaerobic 
filter are located relatively as shown in the drawing, the filter 
ditch following the course of a roadway. The water is finally 
discharged into a little stream, where it mingles with the water 
from a spring, and flows through a meadow. 




SEPTIC TANK 

AND 

ANAEROBIC FILTER 

Genecal Arrangement of Plant 
Fig. 154. — Sectional view of a septic tank combined with an anaerobic filter; to- 
gether with the details of construction and plan of arrangement. 

The septic tank in Fig. 154 is quite similar in construction to the 
others described except that a section of sewer tile takes the place 
of the brick wall between the two parts of the tank. The opening 
0, through which the effluent is discharged, is located a little 
above the center of the tank. 

The anaerobic filter is a tank, rectangular in cross-section, 
made with brick walls and cemented on the inside. The effluent 
from the septic tank enters the anaerobic filter in a chamber, that 
is separated from the main tank by a wooden grating against 
which rests the filter material. As indicated in the drawing, the 
bottom is filled with coarse material; stones or broken tiles 



176 MECHANICS OF THE HOUSEHOLD 

about 4 inches in diameter. Above this is a layer of material 
about 2 inches in diameter and above that another layer of 1-inch 
material; the top is made of gravel. This forms the anaerobic 
filter, in which takes place the bacterial action away from the 
presence of air. The interspaces in the filter material allows the 
effluent from the septic tank to seep through and deposit the 
particles of matter held in suspension. The arrangement is 
such as is best suited to the anaerobic action. Here, shut away 
from the light and air, the organic matter in the effluent under- 
goes disintegration just as would happen in the earth. 

It is evident that some of the matter that should remain in the 
septic tank and be removed as sludge will be carried into the 
anaerobic filter. This will, of course, form an insoluble deposit 
that will accumulate and in the course of time the filter will be- 
come clogged. It should be expected that such a filter will ulti- 
mately need renewing, for this reason the top is made of a slab of 
reinforced concrete that may be raised to allow the removal and 
refilling of the filter material. 

The automatic siphon discharges the water from the chamber 
S, whenever it fills. The discharged water from the siphon is 
conducted into a drain tile, placed in a ditch filled with gravel or 
other loose material, which serves as an additional filter and in 
which the water undergoes a still further purification. This filter 
ditch is constructed as indicated in longitudinal section. The 
water from the siphon enters the tile C and seeping through the 
filling is drained away in the tile shown at D, 

The tiles are not set close together, but the joints are left open 
and covered by pieces of broken tile as shown in H. This is to 
prevent the filter material from entering the tile and thus stop- 
ping the ready flow of the water. 

The filter ditch of the plant will be constructed according to 
the contour of the ground and will follow the natural drainage. 
The course of the ditch^ — if it is desired to use one — will accom- 
modate itself to the character of the ground. The final discharge 
of the water will be determined by the natural drainage. 

That a plant of this kind will work perfectly when new is 
is beyond a doubt but that it will continue indefinitely to give 
perfect satisfaction is not reasonable to expect. The septic tank 
will require cleaning, probably once a year. The anaerobic filter 



SEWAGE DISPOSAL 



177 



will require renewing at intervals, depending on the amount of 
sewage the filter is required to take care of and the rate at which 
the plant is worked, probably once in 4 or 5 years. If the septic 
tank is of insufficient size to readily digest the sewage, the ac- 
cumulation of sludge in the anaerobic filter will be greater than 
should occur. 

It would be only reasonable to suppose that the siphon will 
sometimes refuse to discharge. 
Even though it is an automatic 
siphon, circumstances may cause it 
at times to fail to act. For this 
reason the manhole is placed so 
that the siphon may be inspected 
and repaired, should it be necessary. 
It must not be supposed that once 
such a plant is in place that all of 
the work is over. The success of 
a good sewage-disposal plant of this 
kind demands eternal vigilance. 

In the level areas where the 
possibilities of natural drainage is 
not good, it sometimes occurs that 
plants such as those described are 




Fig. 155. — Septic tank with a settling basin and windmill pump. 

not permissible. To overcome such conditions the plant in 
Fig. 155 represents an installation where the effluent is carried 
several hundred feet through a drain tile before it is finally dis- 
charged into an outlet. This plant is made up of two separate 
tanks, the first acting as a septic tank, while the second tank is 
a settling chamber. The water from the second chamber is 

12 



178 MECHANICS OF THE HOUSEHOLD 

pumped by windmill power and discharged into a drain tile at 
the required height through which it is carried to the place of 
final deposit. 

Limit of Efficiency. — Much that has been written on the 
subject conveys the impression that the septic tank alone, used 
under various conditions, will eliminate disease germs and all 
offending features of sewage and render it a pure water with a 
small amount of residue remaining in the tank. That such is 
not the case is all too evident to many who have constructed 
plants expecting perfect results and have attained only partial 
success. 

It is not reasonable that a plant giving satisfaction under the 
usual conditions could accomplish its purpose under stress of 
work. It is quite evident that the amount of sewage from any 
source cannot be constant. It is equally evident that the effluent 
from the plant cannot always be the same; but with reasonable 
limits of variation, a suitably designed tank ought to take care of 
the sewage from a house at all times and discharge an effluent 
that is reasonably clear and without offending odor. 

It should be kept in mind that, as commonly used, the chief 
office of the septic tank is to do away with the things that offend 
the senses, and not to make an effluent that might serve as drink- 
ing water. It must also be kept in mind that if the disease germs 
enter the plant because of sickness in the house that there is 
every possibility that the germs will be in the discharged water. 

The plant must be located as is directed by the natural sur- 
roundings but the drainage must be away from buildings and 
particularly from wells. 

Small sewage plants are reasonably efficient and add immensely 
to the comfort and healthful conditions of the home. They are 
not perfect in their action but there is excellent reason to believe 
that the plant of ideal construction will yet be attained. 

In a flat country where drainage is difficult, the form of plant 
must be modified to suit the prevailing conditions but some form 
of working plant can always be devised. Small plants do not 
give so efficient results as those of large size but they do very 
acceptable work. To do good service they must receive attention 
but the actual amount of labor they demand is small. Small 
sewage- disposal plants are not expensive nor difficult to construct. 



SEWAGE DISPOSAL 179 

and for the amount of labor and money expended they give 
returns that cannot be estimated. 

In determining the character of plant to be constructed, in 
any particular place, local conditions will in a great measure 
decide the type to be used. The degree of purity to which it 
will be necessary to reduce the effluent will depend on the location 
of the plant and the means of final disposal. If the effluent 
can be run into a stream of sufficient volume, the septic tank alone 
will probably answer the purpose. 

The septic tank reduces sewage to a liquid form which has some 
odor. It may be carried away in an open ditch which has good 
flow, but if allowed to collect in pools it will undergo further 
putrescence and be objectionable. 

It may be possible to use a small creek for final disposal but 
one in which the effluent from a septic tank alone would be objec- 
tionable. In such a case the use of the septic tank combined with 
an anaerobic filter would probably give a permissible degree of 
purity. 

With a plant composed of a septic tank and anaerobic filter, 
sewage is rendered almost free from odor and the effluent will 
not undergo further putrescence when collected in pools. 

In many cases it is desired to purify the effluent still further, 
either because of lack of means for final disposal or because the 
effluent would contaminate the water into which it is discharged. 
In such cases the plant will consist of the septic tank, an anaerobic 
filter and a filter ditch or sand-bed filter. The effluent from such 
a. plant will be clear sparkling water that might be mistaken for 
spring water. 

The design and construction of sewage-disposal plants has been 
made a subject of investigation in a number of State engineer- 
ing experiment stations. In addition, manufacturers of cement 
have prepared descriptive literature that is sent gratis on applica- 
tion. These bulletins contain detailed information as to the 
working properties and construction of private plants to suit the 
various conditions of disposal. The following is taken by per- 
mission of the Universal Portland Cement Co. from then- bulle- 
tin on ^^Concrete Septic Tanks." 

*'The design in Fig. 156 shows a septic taixk as it would appear if 
partly cut away to expose the interior to view, and as if cut in half 



180 



MECHANICS OF THE HOUSEHOLD 



along a center line following its length. This type will be found to 
operate effectively where final disposal is accomplished by sub-surface 



4 Round rods -^6^ 
6'ctoc.i'dbo^e 
bottom of slob- 



No 9 Wire 6'c to c or 2' mesh poultry 
netting i' from bottom. 
li. s'-o'—\ 

^ ^ -\co,erJ^^^ 



4'Cement^^ 
Pipe Inlet^ 

£'Round 
nx/5l'-0'ctocA 




<-//->[<— 


.212' 

o 


—>!<-//-> 


^\W^^1^ 


1 s 


ll ^ 


1 o 1 


fe jV^iphon p 


i^i 1 i I| 1 y 


^lf^« 


tmm 




i : 




*- 


4-0 





-^ SECTION A'A ^ 



Fig. 156. — Septic tank. This shows the construction as if cut away along a 
center line following its legnth, also a section of the siphon chamber and a plan 
of the whole construction. 



; 


■■\/ 


'^J^™*^^ 




IimhbhbhhII^^^^ 


"""I^^Hil 



Fig. 156a — Photographic reproduction of a concrete septic tank, similiar to 
that of Fig. 153. The tank requires only the cover to make it complete. 



irrigation. This system once started is self -operating due to the siphon 
shown in the second, or right-hand compartment, which at regular 



SEWAGE DISPOSAL 181 

intervals empties the contents and discharges them into the line of 
tile from which the liquids leach out through joints into the soil. In a 
tank constructed as shown in the design mentioned, it is very important 
to use a siphon to empty the second compartment at intervals instead 
of allowing a continuous outward flow of contents, because of the tend- 
ency for drains to become clogged when liquids are constantly trickling 
through. 

^'The size of tank required for residence use depends upon the quan- 
tity of sewage to be handled in the first chamber during a day of 24 
hours; therefore, this compartment should be large enough to contain 
an entire day's flow. This frequently amounts to from 30 to 50 gallons 
per person per day, so the required capacity can readily be computed 
from these figures, although it must be remembered that the required 
depth for the tank should be figured from the top of the concrete baffle 
wall or partition which separates the first and second compartments. 
Another point to bear in mind is that the width of the first compartment 
hould be about one-half its length. '' 



CHAPTER IX 
COAL 

Coal is of prehistoric origin, formed from accumulation of 
vegetable matter, supposed to be the remains of immense forests. 
In past ages the deposits underwent destructive distillation from 
great heat and was subjected to pressure, sufficient to compress it 
into varying degrees of hardness. Coal is composed of carbon, 
hydrogen and oxygen, with small quantities of nitrogen and vary- 
ing amounts of sulphur and ash. 

The coals from different geological formations vary in quality 
from the hard dry anthracites to the soft wet lignites, with the 
intermediate bituminous coals; all of which furnish fuels that when 
burned will produce amounts of heat, depending on their com- 
position, the quantity of moisture contained and the conditions' 
of their combustion. 

Carbon, of which coal is principally composed, exists in differ- 
ent combinations, depending on the condition of its formation. 
Part of the carbon is combined with hydrogen to form hydro- 
carbon that may be driven off when heated, and which forms the 
volatile portion of the coal. The remainder of the carbon appears 
in the form of coke — when the volatile matter is driven off — and 
is said to be fixed. The fixed carbon and volatile constituents 
together make up the combustible. 

Other ingredients of coal that require attention are the mois- 
ture, and the incombustible matter that forms ash. Moisture 
varies in quantity from as low as 0.75 per cent, in hard coal to 50 
per cent, in lignite. The amounts of ash in different coals vary 
from 3 to 30 per cent, of the weights of the fuel . 

The heating value of coals differs in amount by reason of the 
variable quantities of fixed and combined carbons, moisture and 
ash. Different coals are compared in value by the number of 
B.t.u. per pound of dry coal that can possibly be developed when 
burned, and with these factors are given the percentages of 
moisture and ash. 

There are no distinct demarkations between different grades of 

182 



COAL 183 

coal. The classifications are made because of their chief charac- 
teristics and they commonly are graded as anthracites, semi- 
anthracites, semi-bituminous and bituminous coals. These 
classes comprehend the most common commercial coals of the 
United States. Aside from those named are forms of coal that 
are occasionally found, such as graphitic anthracite, cannel coal, 
etc., and the various lignites. 

The value of coal as a heat-producing agent is represented by 
the B.t.u. it is capable of turning to useful account. The price 
of coal should be based on the amount of heat it is capable of 
generating when burned. In considering the value of coal for 
any particular purpose, thought must be taken as to its charac- 
teristic properties, for coals that produce excellent results for one 
purpose may be very unsatisfactory in others. Soft coal con- 
taining a large percentage of volatile matter usually produces a 
great amount of smoke and unless carefully fired this will con- 
dense and form accumulations of soot that are objectionable. 
For reasons of this kind bituminous coals are often sold at a lower 
price than their rated heating value might indicate. 

Anthracite or hard coal possesses bright lustrous surfaces when 
newly fractured, that when handled do not soil the hands. It con- 
tains a high percentage of carbon, a small amount of volatile 
matter and little moisture. It is greatly in demand as a domestic 
fuel because it burns slowly with an intense heat, practically 
without flame and produces no smoke. It invariably commands 
a higher price than soft coal, but in heating value is not superior 
to the better grades of soft coal. In furnaces for house heating 
the use of soft coal often gives better satisfaction than hard coal. 

The grades of hard coal found in the market will vary with the 
demand in any locality but those recognized by the trade are: 

Egg Coal will pass through 2%-inch mesh screen. 

Stove Coal will pass through 2-inch mesh screen. 

Chestnut Coal will pass through 1%-inch mesh screen. 

Pea Coal will pass through %-inch mesh screen. 

No. 1 Buckwheat Coal will pass through H-inch mesh screen. 

No. 2 Buckwheat Coal will pass through J-^-inch mesh screen. 

No. 3 Buckwheat Coal will pass through J^-inch mesh screen. 

Hard coal of stove and chestnut sizes are those most commonl}- 
used for domestic heating, because they are well suited for 



184 MECHANICS OF THE HOUSEHOLD 

furnaces and heating stoves. Of the two sizes chestnut coal is 
most largely used and on account of the greater demand, the 
price for this size is usually somewhat in advance of the others ; at 
the same time the smaller sizes — pea and buckwheat coals^ — are 
less in price for the same grade of coal. Under conditions that will 
permit their use the latter coals are an economical form of fuel. 

Bituminous or soft coal represents the' chief fuel of commerce. 
The market prices of these coals are determined largely by reason 
of their reputation as desirable fuel. The variations in price 
depend on the physical qualities, rather than on the amount of heat 
evolved in combustion. The compositions of coals vary markedly 
in different localities and often in the same locality several grades 
are produced. It sometimes happens that from different parts 
of a mine the coal will differ very much in heat value. 

Bituminous coals are roughly classified as coking and free- 
burning. The former is valuable for gas manufacture and for 
production of coke. The coking coals fuse on being heated, 
allowing the volatile portion to escape; and when the gas has 
been all distilled, the residue is coke. When used for gas making, 
the volatile portion forms the illuminating gas. When burned 
in a furnace, the gases from soft coal burn with a yellow flame and 
usually with considerable smoke. The classification of bitumi- 
nous coals differ somewhat in the East from that of the West. 
Eastern bituminous coals are commonly graded: 

A. Run-of-mine coal = unscreened coal as taken from the mine. 

B. Lump coal = that which passes over a bar screen with IJ-^-inch 
openings. 

C. Nut coal = that which passes through a bar screen with 13^-inch 
openings and over one with %-inch openings. 

D. Slack = all that which passes through a %-inch. bar screen. 

Western bituminous coal: 

E. Run-of-mine coal = the unscreened coal as taken from the mine. 

F. Lump coal — divides as 6-inch, 3-inch and l^^-inch according to the 
diameter of the mesh through which the pieces pass the screens. 

G. Nut coal — ^varying from l3-^-inch size to J^-inch in diameter. 

H. Screening = all coal which passes a l3-^-inch screen including the 
dust. 

Heat derived from coal — or any other fuel — in the process 
of combustion is due to oxidation. Combustion or burning 
is caused by rapid oxidation. When oxygen combines with 



COAL 185 

carbon in sufficient quantities, carbon dioxide is formed and at 
the same time heat is liberated. In burning fuel, if the carbon 
is completely oxidized and changed into carbon dioxide, the great- 
est amount of heat is produced. The required oxygen is fur- 
nished by the air, which through the dampers of the furnace 
regulates the rate of combustion. 

Oxidation of Hydrocarbons. — In the oxidation of hydrocarbons, 
as that of burning coal gas, the combination of the elements forms 
carbon dioxide and water. The presence of the water, formed 
in combustion, is often shown in the formation of moisture on 
the bottom of a cold vessel wlien placed over a gas flame. The 
same effect is observed in a newly lighted kerosene lamp, when 
the film of moisture forms inside the cold lamp chimney. As soon 
as the surfaces become heated the moisture is evaporated. Oc- 
casionally, the accumulation of moisture in chimneys, from this 
cause, is sufficient during extremely cold weather to form ice 
in the part of the chimney exposed to the outside air. Chimneys 
have been known to become so stopped by accumulation of ice 
from this cause as to materially interfere with the draft. 

The fixed carbon of the coal, when oxidized, has a constant 
heating value of 14,000 B.t.u. per pound. The volatile hydro- 
carbons develop amounts of heat when burned, depending on 
their composition, and differ in coals from different localities. 
The heat obtained from the volatile part of coal depends on its 
chemical composition and differs very materially; it may be as 
high as 21,000 B.t.u. per pound, or as low as 12,000 B.t.u. per 
pound. 

A high percentage of volatile matter usually indicates a fuel 
that will produce a large volume of smoke, which — unless the 
combustion is complete in the furnace — will deposit soot as 
soon as it is condensed, either in the chimney or in the outside 
air. The ash has no heating value, and the contained moisture 
has a negative heating effect, because considerable heat is re- 
quired to evaporate and raise it to the temperature of the gases 
of the furnace. In burning fuel the moisture uses up the heat 
of combustion in proportion as it appears in the coal. The 
moisture is bought as coal but requires heat to get rid of it; so the 
percentage of water in coal should be considered very carefully. 

It is customary in comparing the heating values of coals, to 



186 MECHANICS OF THE HOUSEHOLD 

state the proportionate parts of fixed carbon, volatile matter, 
moisture and ash as well as the B.t.u. per pound of dry coal. The 
heat value in B.t.u. per pound of fuel is usually obtained by burn- 
ing samples in a calorimeter from which the heat per pound is 
calculated. The heat value of fuels used in power plants are 
often determined by careful tests of the amount of power derived 
for each pound of fuel burned in the furnace. This is done by 
weighing the fuel burned and measuring the water evaporated. 
The ashes are weighed and this weight together with the weight 
of moisture present is subtracted from that of the coal to de- 
termine the amount of combustible of the fuel. The final results 
are expressed by the number of pounds of water evaporated per 
pound of combustible and also the weight to water evaporated 
per pound of coal burned. 

Semi-bituminous coal represents a class between the hard and 
soft grades. It contains less carbon and more volatile matter 
th'an hard coal. It burns with a short flame with very little 
smoke and is valuable as a furnace fuel. The Pocahontas coal 
of West Virginia is an example of this class. Semi-bituminous 
coal is often called smokeless coal, because in burning it produces 
relatively little smoke. It will be noted in the table of heat 
values on page 192 that coal of this variety has high heat-pro- 
ducing properties. It is a very friable coal and for that reason is 
apt to contain considerable dust. As a furnace fuel it produces — 
when carefully fired — very satisfactory results. 

Graphitic Anthracite. — This is a type of coal found in Rhode 
Island and Massachusetts which resembles both graphite and 
anthracite coal. It is gray in color, very hard and burns with 
extreme difficulty. 

Cannel Coal. — This is a variety of bituminous coal, rich in 
hydrocarbons. It burns with a bright flame without fusing and 
is often used for open fires. 

Lignite. — This is a type of fuel that in point of geological for- 
mation represents the condition between true coal and peat. 
Lignite occurs in immense deposits throughout the middle 
portion of the western half of the United States, where beds 20 
feet in depth are not uncommon. It varies in color from black 
to brown and in many localities is known as brown coal. 

When newly mined, lignite contains a large percentage of 
water, sometimes as high as 50 per cent. On account of this 



COAL 187 

large moisture content it has a relatively low calorific value, 
but when dry the amount of heat evolved per pound compares 
very favorably with soft coal. 

Peat." — As a fuel, peat has been used very little in the United 
States on account of the abundance of the better grades of fuel, 
but in many parts of the country it is used locally to a consider- 
able extent. In peat bogs from which the fuel is taken, the peat 
is formed from grasses and sedges which in time produce a car- 
bonaceous mass that becomes sufficiently dense to be taken out in 
sections, with a long narrow spade. The peat is then built into 
piles where after drying it is ready to be burned. 

Wood. — On account of its relative scarcity and correspond- 
ingly high price, wood is no longer a commercial fuel of any con- 
sequence. The low heating value of wood as compared with coal 
makes it a prohibitive fuel except in forest localities. Wood is 
commonly sold by the cord and no attention is given by dealers 
to its value in heat-producing capacity. 

The desirability of wood as a fuel is chiefly that of reputation. 
It is usually considered that hickory is the ideal fire wood, dry 
maple a close second and that oak is next in desirability as fuel; 
following which are ash, elm, beech, etc., depending on the den- 
sity of the wood. The price of wood per cord depends on the 
nearness and abundance of supply. 

The actual heating values of different woods as determined by 
Gottlieb show that per pound of dry wood there is little difference 
in heat value between different kinds of hard woods, and that 
pine gives per pound the highest value of all. The table given 
below was taken from ^^ Steam'' published by the Babcock- 
Wilcox Co. 

Per cent, of B.t.u. per 

Kinds of wood ash pound 

Oak 0.37 8,316 

Ash 0.57 8,480 

Elm 0.50 8,510 

Beech 0.57 8,591 

Birch 0.29 8,586 

Fir 0.28 9,063 

Pine 0.37 9,153 

Poplar 1.86 7,834 

Willow 3.37 7,926 



188 MECHANICS OF THE HOUSEHOLD 

In considering this table it must be kept in mind that the 
values are for dry wood per pound. 

As given in Kent's ^^ Engineer's Pocket Book'' the weights of 
different fuel woods per cord (thoroughly air-dried) are about 
as follows: 

1 cord hickory or hard maple. . 4,500 pounds equal to 1,800 pounds coal 

1 cord white oak 3,850 pounds equal to 1,540 pounds coal 

1 cord beech, red and black oak 3,250 pounds equal to 1,300 pounds coal 
1 cord poplar, chestnut and elm 2,350 pounds equal to 940 pounds coal 
1 cord average pine. 2,000 pounds equal to 800 pounds coal 

The above values in pounds of coal may be taken to represent 
average bituminous coals. As given by Suplees '^Mechanical 
Engineers' Reference Book," eight samples of coals representing 
bituminous coals from mines east of the Mississippi River give 
an average heating value of 13,755 B.t.u. per pound. 

Charcoal. — This is made from wood by driving off the volatile 
constituents; the residual carbon, which forms the charcoal is a 
fuel that burns without smoke or flame. Charcoal is made by 
piling wood in a heap, which is covered with earth. In the bot- 
tom of the heap a fire generates the necessary heat for distilling 
off the volatile matter. Charcoal holds to wood the same re- 
lation that coke bears to coal. 

Coke. — This is the residue from the distillation of coal. It 
comprises from 60 to 70 per cent, of the original coal and contains 
most of the carbon and all of the ash of the coal. Coke is gray in 
color and has a slightly metallic luster; it is porous, brittle and in 
handling gives out something of a metallic ring. It is often sold 
for fuel as a byproduct by gas factories. In heating value gas- 
coke gives about 14,000 B.t.u. per pound when dry and as a con- 
sequence is rated as an excellent fuel. Clean coke burns without 
flame and is capable of producing an intense heat. On account 
of its porous nature it occupies a relatively large volume per ton. 
It is most successfully burned in stoves and furnaces with large 
fire-boxes. 

Gas-coke, which is the residue from the gas retorts, is some- 
what inferior in heating value to coke made in ovens but it is 
an excellent fuel where furnaces are adapted to its use. Gas-coke 
is often stored, by piling it in heaps, in the open and on account 



COAL 189 

of its porous nature it absorbs considerable moisture. Where 
exposed to the weather the amount of contained moisture de- 
pends on the amount of rain or snow the coke has absorbed. This 
amount is easily determined by weighing a fair sample and driv- 
ing off the moisture in an oven. The sample should be weighed 
several times until the weight remains constant. 

Briquettes. — Briquetted coal and other fuels are produced 
by compressing coal dust or other powdered fuel, mixed with coal 
tars or other bituminous binder in sufficient quantity to cause 
the adhesion of the particles when pressed into form under great 
pressure. Owing to the relative cheapness of fuel, briquettes 
have been used but very little in the United States. With the 
advance in the price of coal of the past few years, they have 
found a place on the market and have become a common form 
of fuel. 

The heat value of briquettes will depend on the kind and 
quality of material that enters into their composition. Quite 
generally, they produce heat equal to the average grade of soft 
coal. In the Northwest briquettes made of West Virginia 
semi-bituminous coal sell at the same price as run-of-mine 
coal of the same quality. Their use has proven satisfactory 
as a furnace fuel and they will very likely be sold in increasing 
quantities. 

Comparative Value of Coal to Other Fuels. — Until a compara- 
tively recent time, coal has been sold by weight and reputation 
alone; but conditions are rapidly approaching, which will require 
it to be sold according to its composition and heating value. 
Among manufacturers and others using large quantities of fuel, 
the practice of contracting for coal by specification is becoming 
increasingly common. The determining factors are the amounts 
of moisture, ash, sulphur, carbon, and volatile matter the coal 
contains, as well as the size of the pieces and freedom from dust. 
In a few of the most progressive cities, coal dealers are required 
to supply coal for schools and other municipal uses, which has 
been subject to the approval of the City Engineer. The time is 
not far distant when dealers will be required to submit samples 
of' all fuel, for sale to the public, to the examination of the munici- 
pal authorities. 



190 MECHANICS OF THE HOUSEHOLD 

The following table of the heating values of various fuels is 
taken from Benson's ''Industrial Chemistry." 



British Thermal Units for One Cent from Different Fuels 

Acetylene, from carbide at 10 cents per pound 600 

Denatured alcohol, at 40 cents per gallon 2,000 

Air gas (from gasoline, 80°Be at 25 cents per gallon) . 3,000 

Water gas, at $1 per 1000 cubic feet 3,000 

Coal gas, at $1 per 1000 cubic feet 6,500 

Gasoline, at 20 cents per gallon 7,500 

Kerosene, at 15 cents per gallon 11,000 

Natural gas, at 50 cents per 1000 cubic feet 18,000 

Charcoal, at 10 cents per bushel (15 pounds) 20,000 

Petroleum at 5 cents per gallon 30,000 

Producer gas, from anthracite, $7 per ton 30,000 

Producer gas, from coke, $5 per ton 36,000 

Anthracite, at $7 per ton 46,000 

Producer gas, from soft coal, at $3 per ton 50,000 

Coke, at $5 per ton 54,000 

Mond producer gas from soft coal, at $3 per ton 65,000 

Soft coal, at $3 per ton 80,000 



Price of Coal. — The value of coal as a fuel will depend on the 
amount of heat it is capable of producing when burned; its price 
should therefore be determined by the heating value per pound 
of fuel as purchased. Secondary determining factors in price are 
those of convenience of handling and the difficulty in burning the 
fuel such as the size and uniformity of the pieces, the formation 
of clinkers, smoke and accumulation of soot. Soft coals, contain- 
ing a large amount of volatile matter, usually produce much soot 
and smoke and as a consequence sell for a lower price than coals 
that produce little smoke. 

The selection of fuels will depend on the type of heating plant 
in use, whether by stoves or by furnaces. If by stoves, whether it 
is possible to use soft coal as a fuel. The automatically fed 
stove, of the base-burner type, are usually designed for the use of 
hard coal and in such stoves the use of soft coal would not be 
possible. Other stoves and furnaces are usually capable of burn- 
ing soft coal with varying degrees of satisfaction, depending on 
the design and surrounding conditions. 



COAL 191 

The following prices, from the local market, show the usual 
ratings of various fuels in common use. These prices vary with 
the locality and somewhat with the season. It is usually possible 
to purchase coal at some reduction in price during the summer 
months when the demand for coal is light. 



Hard coal — stove size $10.25 per ton 

Hard coal — ^nut size 10 . 50 per ton 

Semi -bituminous — ^run-of-the-mine 9 . 00 per ton 

Pennsylvania bituminous — run-of-the-mine 7.50 per ton 

Soft coal — Ohio — run-of-the-mine 7 . 50 per ton 

Soft coal — Illinois — ^bituminous — run-of-the-mine 7 . 50 per ton 

Soft coal — Iowa — ^bituminous — run-of-the-mine 7 . 50 per ton 

Briquettes-mixture semi-bituminous coal dust 9 . 00 per ton 

Wood (oak), sawed, stove length and split 8.50 per cord 



The price of coal is determined in many localities by the dis- 
tance from the sources of supply and the means of transportation. 
The fact that coals from all of the principal mining areas from 
Pennsylvania, west to Iowa, are sold at points in the Northwest 
for the same price, is due in greatest measure to transportation 
rates on the Great Lakes. The prices of Eastern coals at Duluth 
are such that in competition with Western coals they are sold at 
the same price as is shown by the table. 

It is usually impossible for the average householder, or even 
the dealer, to determine definitely the exact locality from which 
his fuel is mined. Even when such information is obtainable, 
the quality is still in doubt, unless analysis is obtainable by sample. 
The data given in the following tables is such as will furnish a fair 
knowledge of the relative heating values of coals from the prin- 
cipal mining areas of the United States. The data was obtained 
from a considerable number of authorities but chiefly from the 
reports of the United States Geological Survey. The different 
items are not intended to be exact, they merely represent reliable 
average conditions. 

The varying conditions of available heat and percentage of 
moisture given in the following table are such as to be of little 
use to those unaccustomed to problems of this kind, unless a 
systematic method of comparison is made of the different fuels. 



192 



MECHANICS OF THE HOUSEHOLD 



Approximate Composition and Calorific Value of Typical American Coals 



1 

Local- 
ity 


2 
Kind of coal 


3 

Number, 
of saniples 
examined 


Moisture 


5 

Volatile 
matter 


6 
Fixed 
carbon 


7 

B.t.u. per 

pound 

dry coal 


Ash 


Pa... 


Anthracite 


12 


5.05 


5.52 


82.54 


12,682 


11.53 


Md.. 


Semi- 
bituminous 


5 


2.39 


17.73 


75.44 


14,530 


7.40 


Pa. .. 


Semi- ^ 
bituminous 


15 


3.60 


19.26 


74.46 


14,211 


8.32 


W.Va 


Semi- 
Bituminous 


12 


2.50 


19.00 


75.70 


14,758 


5.24 


Ala.. 


Bituminous 


6 


3.55 


29.99 


59.24 


13,522 


10.73 


Ark.. 


Bituminous 


2 


1.42 


16.58 


73.37 


14,205 


10.05 


Colo.. 


Bituminous 


6 


9.89 


37.34 


52.53 


12,325 


10.32 


111.... 


Bituminous 


22 


10.31 


36.73 


50.52 


11,504 


12.73 


la.... 


Bituminous 


8 


7.72 


39.15 


50.54 


12,656 


10.33 


Kan.. 


Bituminous 


3 


4.25 


32.20 


51.17 


12,031 


13.75 


Ky... 


Bituminous 


9 


5.99 


34.58 


56.56 


13,341 


8.86 


Mo... 


Bituminous 


9 


11.52 


37.85 


48.11 


12,398 


14.04 


Ohio. 


Bituminous 


14 


5.65 


38.51 


50.59 


12,839 


10.65 


Okla. 


Bituminous 


3 


5.72 


34.83 


52.76 


12,648 


12.41 


NM.. 


Bituminous 


1 


12.17 


36.31 


51.17 


12,126 


12.52 


Pa. .. 


Bituminous 


15 


2.44 


33.41 


58.31 


13,732 


8.40 


Tenn. 


Bituminous 


4 


2.53 


36.58 


58.21 


14,098 


5.47 


Tex.. 


Bituminous 


3 


3.84 


35.05 


48.99 


12,302 


15.96 


Va. . . 


Bituminous 


5 


2.71 


31.32 


62.47 


14,025 


6.92 


W.Va 


Bituminous 


10 


2.61 


33.92 


58.80 


14,094 


7.27 


Colo.. 


Lignite 


6 


19.75 


45.21 


45.85 


10,799 


8.93 


N. D. 


Lignite 


5 


35.93 


44.33 


43.21 


10,420 


12.45 


Tex.. 


Lignite 


6 


30.86 


44.06 


39.21 


10,297 


16.76 


Wyo. 


Lignite 


4 


14.71 


48.47 


44.49 


11,608 


7.035 



The following table was prepared from the date of that preceding 
combined with the prices of various coals to be obtained in the 
local market. The table is intended to present a method of 
comparing the values of fuels from different coal areas. The 
consumer is interested to know the amount of heat purchased in 
the form of fuel. The table shows in the column headed ^'Heat 
per $1/' the number of B.t.u. purchased for $] in coal; the number 
of available B.t.u. in the different kinds of coal may be taken as a 
relative comparison of their values as fuel. 

The gas-coke in the table is that sold by the local gas company. 
The amount of moisture in this case is relatively high because of 



COAL 



193 



the fact that the coke is stored in a yard exposed to the weather, 
where it absorbs all precipitated moisture. A less amount of 
moisture would give a higher value for the same fuel. 



Kind of coal 


Price 
per 
ton 


Per 
cent., 
water 


B.t.u. per 
100 pounds 


B.t.u. to 

evaporate 

water 


B.t.u. per 

100 ^ cost 

per 100 

pounds 


Heat per $1 


Bituminous 
Pennsylvania 


$7.50 


2.44 


1,340,000 


- 3,439 = 


1,336,565 
$0,375 ~ 


3,564,000 B.t.u. 


Semi- 
bituminous . 
West Virginia 


$9.00 


3.06 


1,420,000 - 


- 4,315 = 


1,415,685 
$0.45 ~ 


3,145,000 B.t.u. 


Gas-coke 


$7.00 


10.00 


1,117,900 - 


- 16,888 = 


1,101,012 
$0.35 ~ 


3,145,000 B.t.u. 


North 

Dakota 

lignite 


$4.50 


35.90 


668,000 - 


- 50,728 = 


607,282 
$0,225 ~ 


2,703,000 B.t.u. 


Bituminous 
Illinois 


$7.50 10.31 


1,032,000 - 


14,398 = 


1,017,602 
$0,375 = 


2,980,000 B.t.u. 


Bituminous 
Iowa 


$7.50 


13.10 


1,012,000 - 


- 18,471 = 


994,529 
$0,375 


2,652,000 B.t.u. 


Hard coal 
Pennsylvania 


$10.50 


3.05 


1,230,000 - 


- 4,195 = 


1,225,905 
$0,525 = 


2,335,000 B.t.u. 



Semi-bituminous coal commands considerable favor as a 
house-heating fuel, because of the fact that it burns with much 
less smoke than bituminous coal. In available heat it is con- 
siderably above the Western bituminous coal and it sells at a 
price $1.50 higher per ton. The reason for the difference in 
price is not so much on account of its heating value, as because 
of relatively small amount of smoke produced in combustion. 
Other coals capable of producing more heat are sold at less price 
because of smoke and soot produced in burning. 

Hard coal at $10.50 is the most expensive coal of all. The 
ratio of available heat units per $1 for hard coal, as compared 
with the best soft coal, is as 23 is to 35. This means that at the 
stated prices those who burn hard coal pay the additional price, 
because of the physical properties it possesses. 

In constructing the above table, 100 pounds of coal was taken 
as a unit of comparison. The price per ton is that given in the 
table of local prices. The per cent, of moisture and the B.t.u. 
per pound of fuel was taken from table on page 192. 

13 



194 MECHANICS OF THE HOUSEHOLD 

In explaining the method by which the different items were 
obtained, it will be necessary to discuss briefly the condition of 
combustion and the heat losses that take place when fuel is 
burned. 

The moisture in the fuel is the undesirable part, b.ecause it 
requires a large amount of heat to dispose of it. It is looked upon 
as so much water, that must be raised in temperature from that 
in which it is taken from the coal bin to the temperature and con- 
dition of vapor in which it passes into the chimney. When the 
fuel enters the furnace the water is heated to the boiling point. 
In changing temperature it absorbs i B.t.u. for each pound of 
water, through each degree of change. Suppose that, as in 
the case of Pennsylvania bituminous coal which contains 2.44 
pounds of water to each 100 pounds of coal, the coal entering 
the furnace was at 50°F. To raise its temperature to the boiling 
point (212°r.) required a change of 162°. The 2.44 pounds of 
water raised this amount 

162 X 2.44 = 395.28 B.t.u. 

To change the 2.44 pounds of water, into steam at the atmos- 
pheric pressure requires 969.7 B.t.u. (heat of vaporization), 
practically 970 B.t.u. per pound of water. The heat required 
to vaporize 2.44 pounds of water is 

2.44 X 970 = 2366.80 B.t.u. 

The vapor is now raised in temperature, to that of the furnace, 
which we may assume is 1200°F. The furnace being at atmos- 
pheric pressure the vapor merely expands in volume as a gas. 
The specific heat of steam at atmospheric pressure is 0.464; 
that is, 1 pound of steam requires only 0.464 B.t.u. to raise it a 
degree, and 2.44 pounds of water will absorb 

0.464 X 2.44 X 1200 = 1356.00 B.t.u. 

Of this last amount of heat, approximately 50 per cent, is 
recovered as the gases pass through the furnace. The total 
loss of heat due to the evaporation of the water is 

Raising temperature from normal to 212° 395 B.t.u. 

Evaporation 2,366 B.t.u. 

Changing temperature of vapor, less 50 per cent. 678 B.t.u. 

Total heat loss 3,439 B.t.u. 



COAL 195 

In the 100 pounds of coal under consideration, there is 100 
pounds, less 2.44 pounds of water, or 97.56 of dry coal, each 
pound of which contains 13,732 B.t.u. as given by the table on 
page 193. This gives 

97.56 X 12,682 = 1,339,753 = practically 1,340,000 B.t.u. 

From this quantity is subtracted the loss of heat, 3439. 

1,340,000 - 3439 = 1,336,561 B.t.u. 

This represents the total available heat in 100 pounds of 
coal. If this quantity is now divided by the cost of 100 pounds 
of coal at $7.25 per ton, the result, 3,564,000 B.t.u., will be the 
available heat bought for $1 as given in column 7 of the table. 



CHAPTER X 
ATMOSPHERIC HUMIDITY 

The physical effect of atmospheric humidity has come to be 
recognized by all who deal in problems of house heating, sani- 
tation and hygiene. The difference in effect of dry atmosphere, 
from that of air containing a desirable degree of moisture, is 
very noticeable in all buildings that are artificially heated. The 
effect of dry air is made apparent in the average home during the 
winter months by the shrinking of the woodwork and furniture. 
The absorption of the moisture from the building which is usually 
termed ^'drying out,'' causes the joints in the floors and casements 
to open, doors to shrink until they fail to latch and drawers that 
have opened with difficulty during the summer then work freely. 

Winter time is the season of prevalent colds, chaps and rough- 
ness of the skin, not so much on account of cold weather as be- 
cause of dry air. The skin which is normally moist is kept dry 
by constant evaporation with the attending discomfort of an 
irritated surface and the results which follow. 

The humidity of the air in which we live and on which we 
depend for life has much to do with the bodily comfort we derive 
in existence, and is suspected of being the cause of many physical 
ailments. Ventilation engineers not only recognize this con- 
dition but have found means of controlling it. It is possible 
to so control atmosphere temperature and humidity of buildings 
as to produce any desired condition. 

Humidity of the Air. — The amount of water vapor in the air is 
called the humidity of the air. It may vary from a fraction of a 
grain per cubic foot in extremely cold weather, to 20 grains per 
cubic foot during the occasional hot weather of summer. 

Since the amounts of moisture that air will hold depends on 
its temperature, and as the air is ordinarily only partly saturated, 
the varying amount of moisture are expressed either as relative 
humidity and stated in per cent, saturation or in the actual weight 
of water in grains per cubic foot and known as absolute humidity, 

196 



ATMOSPHERIC HUMIDITY 197 

The relative humidity of the atmosphere is the amount of 
moisture contained in a given space as compared with the amount 
the same air could possibly hold at that temperature. Warm 
air will hold more moisture than the same air when cold. Air 
absorbs water like a sponge to a point of saturation. When the 
air is filled with moisture, any change which takes place to reduce 
the temperature also reduces its capacity to hold the water 
vapor and the excess is deposited as dew. This supersaturation 
ordinarily takes place near things which lose their heat faster 
than the surrounding air and the nearest colder surface acts as a 
condenser to receive the drops of dew. Grass being in convenient 
position is the commonest receptacle for dew formation. If the 
dew forms in the air it falls as rain, but if the temperature of the 
dew-point is below freezing, the dew immediately freezes and 
snow is the result. 

In the consideration of problems that involve atmospheric 
moisture, both relative and absolute humidity are factors of 
common use, that are capable of exact determination. The rela- 
tive humidity of the air is most readily determined and as it ex- 
presses the state of the atmosphere in which plants and animals 
live and thrive, as opposed to other conditions of humidity in 
which they sometimes sicken and die, it is one of the indicators 
of the quality of atmospheric air. 

In the subject of ventilation, which is undertaken later, it will 
be found that a definite knowledge of atmospheric humidity has 
much to do with the successful operation of ventilation apparatus. 
Most people recognize the '^ balmy air of June^' without realizing 
just why at the same temperature other seasons are not so delight- 
ful. In reality it is the condition of atmospheric humidity 
combined with an agreeable temperature that gives the kind of 
air in which we find the greatest degree of comfort. 

The effect of moderately warm humid air is that of higher 
temperature than the thermometer indicates. When the atmos- 
phere is near the point of saturation, the evaporation which 
usually goes on, from the surface of the body, practically ceases. 
In summer time a temperature of 85°F. with relative humidity 
of 90 per cent, saturation seems warmer than a temperature of 
100° at 40 per cent, saturation, because of the cooling effect 
produced by the increased evaporation due to the drier air. 



198 MECHANICS OF THE HOUSEHOLD 

In winter, when most of the time is spent indoors, in an atmos- 
phere that is very dry, the sensation of discomfort produced by 
the lack of humidity oftentimes leads to physical derangements 
that would never appear under more desirable conditions. The 
cause of many ailments of the nose, throat and lungs during the 
winter months is attributed by physiologists to breathing almost 
constantly the dry vitiated indoor air. The cause of dry air in 
buildings is not difficult to explain ; it is a great deal more difficult 
to realize that the lack of water breeds so much discomfort. 

In order to express the condition of humidity that may exist 
in the average dwelling, office or school-room during the winter, 
it is most convenient to refer to the results of varying atmospheric 
conditions that are given in Table 1 — Properties of Air — which 
appears below. In the second column of the table, under the 
heading ^^ Weight of vapor per cubic foot of saturated air,'' 
will be found the amount of moisture in grains per cubic foot 
that will be required to humidify air at different temperatures. 
It will be seen that at 10° the air will contain, when fully saturated, 
only 1.11 grains of water, while at 70° temperature the same air 
would hold 8 grains of water. These amounts will be found in the 
column opposite the temperature readings. It is at once evident 
that when saturated air at 10° is raised to normal temperature 
70°, the original amount of moisture is contained in an at- 
mosphere capable of holding 8 grains of water. Its relative 

humidity will therefore be -^^— > practically 14 per cent, satur- 

o 

ated. Unless moisture is received by the air from some other 
source this condition will produce a very dry atmosphere. 

The normal atmospheric temperature of 70°r. with a relative 
humidity of 50 to 60 per cent, saturation produces a condition 
that is one of agreeable warmth to the average person in health 
and is recognized as the atmosphere most desirable. To some, 
this state of temperature and humidity is that of too much 
warmth and a temperature of 68°, with the same humidity, is 
most agreeable. At the same temperature, a reduction of the 
humidity to 20 per cent, saturation will produce a feeling of dis- 
comfort and the sensation will be that of a lack of heat. The 
cause for this latter feeling is due to excessive evaporation of 
moisture from the body. 



ATMOSPHERIC HUMIDITY 



199 





Table I. — Properties of 


Air 




Tempera- 
ture of the 
air 


Weight of 

vapor per 

cubic foot of 

saturated 

air 


Weight of 

cubic foot of 

saturated 

air 


Tempera- 
ture of the 
air 


Weight of 

vapor per 

cubic foot of 

saturated 

air 


Weight per 

cubic foot of 

saturated 

air 


Fahrenheit 


Grains 


Grains 


Fahrenheit 


Grains 


Grains 


10° 


1.11 


589.4 


41° 


3.19 


550.8 


11 


1.15 


588.1 


42 


3.30 


549.6 


12 


1.19 


586.8 


43 


3.41 


548.4 


13 


1.24 


585.5 


44 


3.52 


547.2 


14 


1.28 


584.2 


45 


3.64 


546.1 


15 


1.32 


582.9 


46 


3.76 


544.9 


16 


1.37 


581.6 


47 


3.88 


543.7 


17 


1.41 


580.3 


48 


4.01 


541.3 


18 


1.47 


579.1 


49 


4.14 


542.5 


19 


1.52 


577.8 


50 


4.28 


540.2 • 


20 


1.58 


576.5 


51 


4.42 


539.0 


21 


1.63 


575.3 


52 


4.56 


537.9 


22 


1.69 


574.0 


53 


4.71 


536.7 


23 


1.75 


572.7 


54 


4.86 


535.5 


24 


1.81 


571.5 


55 


5.02 


534.4 


25 


1.87 


570.2 


56 


5.18 


533.2 


26 


1.93 


569.0 


57 


5.34 


532.1 


27 


2.00 


567.7 


58 


5.51 


534.9 


28 


2.07 


566.5 


59 


5.69 


529.8 


29 


2.14 


565.3 


60 


5.87 


528.6 


30 


2.21 


564.1 


61 


6.06 


527.0 


31 


2.29 


562.8 


62 


6.25 


526.3 


32 


2.37 


561.6 


63 


5.45 


525.2 


33 


2.45 


566.4 


64 


6.65 


524.0 


34 


2.53 


559.2 


65 


6.87 


522.0 


35 


2.62 


558.0 


66 


7.08 


521.7 


36 


2.71 


556.8 


67 


7.30 


520.0 


37 


2.80 


555.6 


68 


7.53 


519.4 


38 


2.89 


554.4 


69 


7.76 


518.3 


39 


2.99 


553.2 


70 


8.00 


517.2 


40 


3.09 


552.0 









The evaporation of moisture is always accompanied with the 
loss of heat required to produce such change of condition. This 
is known as the heat of vaporization and represents a definite 
amount of heat that is used up whenever water is changed into 
vapor. No matter what its temperature may be — whether hot 



200 MECHANICS OF THE HOUSEHOLD 

or cold — when water is vaporized, a definite amount of heat is 
required to change the water into vapor. 

Water may be evaporated at any temperature; even ice evapo- 
rates. A common instance of the latter is that of wet clothes 
which ^'freeze dry'^ in winter weather when hung on the clothes 
line. The rate at which evaporation takes place depends on the 
dryness of the surrounding air and the rapidity of its motion. 
In dry windy weather evaporation is most rapid. 

As before stated, whenever water evaporates — at no matter 
what temperature — a definite quantity of heat is necessary to 
change the water into vapor. The exact amount of heat required 
to produce this change varies somewhat with the temperature 
and atmospheric pressure but it always represents a large loss 
of heat. At the boiling point of water (212°r.) the heat of 
vaporization is 970 B.t.u. for each pound of water evaporated, 
but at a lower temperature it is greater than that amount. At 
the temperature of the body (98.6^) the heat necessary to evapo- 
rate a pound of moisture, from its surface is 1045 B.t.u. 

It is the absorption of heat due to evaporation that cools the air 
of a sprinkled street. The more rapid the evaporation the more 
pronounced is the decline of temperature in the immediate vicin- 
ity. The same effect is produced when moisture is evaporated 
from the surface of the body. The acceleration of evaporation 
caused by a breeze or the blast of air from an electric fan is that 
which produces the chilling sensation to the body. During 
winter weather the effect of the cold wind is rendered more severe 
by evaporation of moisture from the body. In health, the body 
being in a slightly moist condition, the evaporation which goes 
on from its surface is what keeps it cool in warm weather, but 
if on account of excessive dryness of the surrounding air the 
evaporation is very rapid, ^ sensation of cold is the result. 

Not only does excessively dry air produce the sensation of 
chilliness but the loss of heat from the body due to sudden or 
long exposure effects the general health and is conducive to chills 
that are followed by fever. In health the temperature of the 
body is constant and normally 98.6°F.; any condition that reduces 
that temperature tends toward a lowering of vitality and the 
consequent inability to withstand the attack of disease. In a 
very dry atmosphere the skin, instead of being slightly moist, is 



ATMOSPHERIC HUMIDITY 201 

kept dry, the result of which is the irritation that produces chaps 
and roughness of the surface. 

Reports of the U.S. Weather Department show that the relative 
humidity of Death Valley, which is the driest and hottest known 
country, during the driest period of the year — between May and 
September— averages 15.5 per cent, saturation. In winter, 
many buildings, particularly offices and school buildings are not 
far from that atmospheric condition, constantly. Under the 
usual conditions of house heating, there is an almost absolute 
lack of means to give moisture to the air. Almost without 
exception steam-heating plants and hot-water heating plants 
in office buildings and dwellings are without any provision for 
changing the atmospheric humidity. 

In school buildings that are not kept under a more desirable 
condition of temperature and humidity, the general health is 
impaired and the behavior of the pupils very markedly influenced. 
The tension of a school-room full of fidgety nervous children can 
be very promptly and greatly reduced by the introduction of 
water vapor into the air to 50 per cent, saturation. 

All modern school buildings, auditoriums, etc., are provided — 
aside from the heating plants — with means of ventilating in 
which the entering air is washed and humidified to the desired 
degree, before being sent into the rooms. 

The popular conception of the hot-air furnace method of heat- 
ing is that it produces particularly dry air, when in reality it is 
the only type of house-heating plant in which any provision is 
made for adding water to the air. These furnaces are usually 
furnished with a water reservoir by use of which the humidity 
may be raised to a desirable point. 

Much of the water which enters the air of the average home, 
during winter weather, comes from the evaporation that goes on 
in the kitchen. Usually on wash days the humidity is raised to 
a marked degree and that day is commonly followed by a short 
period of agreeable atmospheric condition. The arrangement 
of many houses is such that a much-improved condition of hu- 
midity might be obtained from the kitchen by continuous evapo- 
ration of water from a tea-kettle. 

The prevailing impression seems to exist that when air is 
heated, it loses its moisture. . In reahty, air that is heated only 



202 



MECHANICS OF THE HOUSEHOLD 



o ^ 



o 
d 














































-- 


CO 


to 


CO 


00 


OS 


^ <M 


O 

f-H 








































o 


<N 


^ 


to 


i> 


OS 


o 


<N 


CO 


-* CO 


o 

00 




































o 


CO 


»o 


CO 


00 


o 


^ 


CO 


Tj* 


CO 


t^ 


00 o 
1-1 (N 


o 
































(N 


TJH 


CO 


l> 


OS 


^ 


(N 


"^ 


to 


l> 


00 


g 


CI 


<N CO 


o 
CO 


























1-1 


CO 


lO 


l> 


05 


o 


(N 


-^ 


to 


t^ 


00 

1-1 


o 


<M 






to 


CO l> 


o 
i6 






















(N 


Tj< 


CO 


00 


o 


(M 


Tj^ 


lO 


t^ 


00 


o 

(N 


1-1 


CO 


(M 


to 




00 


§ 


CO CO 


o 
















o 


CO 


lO 


00 


o 


(N 


'•^ 


»o 

I-H 


»> 


OS 


o 




CO 


»o 


CO 


(M 


00 


o 

CO 


1-1 

CO 


CO 


CO 

CO 


n< lo 

CO CO 


. o 

CO 












(N 


o 


l> 


OS 


i-H 


"<!*< 


CO 


t^ 


OS 


?Q 






lO 




00 


OS 


CO 


CO 


CO 
CO 


CO 


to 

CO 


CO 

CO 


CO 


00 OS 
CO CO 


o 

(M 

1-i 






^ 


'^ 


1> 


OS 


1-H 


"^ 


CO 


00 


o 




CO 




CO 


00 


OS 


o 

CO 


CSJ 

CO 


CO 

CO 


CO 


lO 
CO 


CO 
CO 


00 

CO 


OS 
CO 


o 


o 




(N CO 


o 


-* 


CO 


Oi 




T*< 


CO 


00 


(N 


CO 




CO 


S 


§ 


I-H 

CO 


CO 


CO 
CO 


»o 

CO 


CO 

CO 


CO 


00 

CO 


OS 
CO 


o 






CO 




to 


CO 


t> 00 


o 
d 


(N 


Tj< 


l> 


Oi 


1-H 


CO 


CO 


00 


05 


CO 


U 


S 


S 


s 


s 


OS 
CO 


o 


1-1 




CO 




lO 


CO 




00 


OS 


o 
to 


o 
to 


r-l (N 

to to 


o 

d 


O 
<M 


CO 




l> 


OS 


1-i 
CO 


CO 
CO 


CO 


CO 

CO 


CO 


OS 
CO 


o 


i-H 




CO 




lO 


CO 




00 


OS 


s 


1-1 
to 


s 


S 


CO 

to 


to 


s 


CO CO 
lO to 


o 

00 


OS 


CO 


CO 

CO 


CO 


CO 


00 
CO 


o 


tH 


CO 




lO 
rH 


CO 


^ 


00 


OS 


o 

iO 


1-1 

lO 


lo 


s? 


s 


§ 


s 


§ 


to 


00 

to 


00 

to 


OS 

to 


o 

CO 


O rH 

CO CO 


o 


CO 


CO 


^ 


CO 




CO 




00 


05 


»o 




CO 

to 




»o 


to 

lO 


CO 

lO 


lO 


s 


§ 


g 


o 

CO 


1-1 

CO 


CO 


CO 


CO 

CO 


CO 
CO 


CO 


CO 


to CO 

CO CO 


o 
d 


CO 


00 


05 


»o 




CO 






CO 




00 


OS 


o 

CO 


o 

CO 


CO 


CO 


CO 
CO 


CO 
CO 


CO 


s 


to 

CO 


§ 


CO 
CO 


CO 


§ 


00 
CO 


00 

CO 


OS 
CO 


o o 


o 




CO 


00 


OS 


o 

CO 


CO 


(M 

CO 


CO 


CO 
CO 


CO 


CO 


§ 


CD 
CO 


CO 


CO 


g 


g 


i 


o 


o 




1-1 






CO 

t> 


CO 






Tt< to 


o 


CO 


CO 


CO 

CO 


CO 


00 

CO 


00 

CO 


OS 

CO 


g 


o 








CO 


CO 




s 


12 


g 


s 


g 


CO 

t> 






t* 
t^ 


00 


00 


OS 


OS 


OS OS 


o 

CO 


CO 


CO 






CO 


CO 






00 


00 


OS 


OS 


OS 


o 

00 


§ 


00 


1-1 

00 


00 


00 


00 


00 


00 


S8 


S 


CO 

00 


z 


s 


s 


rJH to 
00 00 


o 


00 


00 


CO 

00 


CO 
00 


00 


^ 


00 


uo 
00 


00 


00 


§ 


s 


CO 
00 


00 




00 


00 


00 
00 


28 


s 


§§ 


00 

00 


00 

00 


S 


OS 
00 


§ 


§ 


OS 
00 


OS <7S 


o 


1-t 


05 


05 


Oi 


OS 


OS 


OS 


OS 


05 


CO 
05 


CO 
OS 


CO 
05 


CO 
OS 


CO 
OS 


CO 
OS 


CO 
OS 


OS 


OS 


OS 


OS 


OS 


OS 


OS 


OS 


OS 


s 


s 


s 


to to 

OS OS 


i 

< 


CO 


CO 
CO 


CO 


00 
CO 


OS 
CO 


o 


^ 




CO 






CO 


t^ 

■<!*< 


00 


OS 


s 


iO 


(M 

iO 


CO 

»o 


»o 


lO 

to 


CO 

to 


to 


00 

to 


OS 

to 


g 


CO 


CO 


CO ^ 

CO CO 



ATMOSPHERIC HUMIDITY 



203 



■II = 



o 

i 


CO 


»o 


CO 


t> 


OJ 

1-1 


o 


r-4 




CO 




lO 


CO 




00 


s 


s 


CO 


CO 


CO 


»o 

CO 


CO 


00 
CO 


OS 
CO 


o 

rt< 


rH 




CO 


rH 
rH 


to to 


o 

oi 


r-l 


00 

i-H 


s 


<N 




CO 






CO 




00 
CS| 


OS 


o 

CO 


CO 


CO 


CO 


CO 


CO 


CO 


00 

CO 


OS 
CO 


o 


-* 


rH 


CO 


rH 
rl< 


lO 
rlH 


CD 
rH 


><*< rH 


o 

00 


rH 




CO 


C^ 




CO 




00 


S 


g 


CO 


CO 


CO 
CO 


CO 


CO 


CO 


t> 

CO 


00 
CO 


OS 

CO 


-^ 




CO 


rH 


lO 

rH 


CD 
rH 




l> 


00 

rH 


?g 


o 




CO 




00 


05 


U 


CO 


CO 


CO 
CO 


CO 


CO 


CO 


CO 
CO 


s 


CO 


00 
CO 


o 


1-1 


c^ 


CO 




if5 


CO 




00 


OS 


o 
•o 


to 


rH C^ 

to to 


o 

CD 


00 


Oi 
C^ 


O 
CO 


I-H 
CO 


CO 


CO 

CO 


CO 


iO 
CO 


CO 
CO 


CO 


00 

CO 


00 
CO 


OS 
CO 


o 


TH 


'^ 


CO 




rJH 


CO 


t^ 

'^t* 


00 


OS 


o 

lO 


to 


»o 


lO 


s 


rH rH 

IO to 


o 


CO 


CO 
CO 


T}4 

CO 


CO 


CO 

CO 


CO 


00 

CO 


OS 
CO 


o 


o 


TJH 




Tt< 


CO 


Tt< 




CO 




00 


OS 


o 

lO 


1-1 


s 


s 


s 


s 


lO 

iO 


g 


gfe 


o 

tH 


g 


CO 


00 

CO 


a 

CO 


o 
-* 


o 


r-t 




CO 








CO 


CO 






OS 


g 


to 


»o 


-co 

lO 




rH 
lO 


s 


§ 


»o 


J5 


s 


gg 


o 

CO 
1-4 


o 


rfi 




CO 






iO 

^ 


CO 


CO 


l> 


00 


00 


OS 


o 


o 


iO 


lO 


CO 


lO 


lO 
iO 


CO 

»o 




fe 


s 


g 


OS 
lO 


§ 


CD 


r^ C<1 

CD CD 


o 






CO 




l^ 

"iH 


00 


OS 


OS 


O 


I-H 


1-1 


(M 




CO 




lO 




CO 
UO 




00 


g 


§ 


o 

CO 


1-t 

CO 


1-1 

CO 


CO 


s 


CO 
CD 


rH rH 
CO CO 


o 


00 
rt4 


05 


§ 


»o 


lO 




S 


s 


S 


s 






CO 




l> 




00 


OS 


o 

CO 


CO 


2 


CO 


s 


s 


s 


»o 
•CO 


lO 
CO 


CO 
CD 


CD l> 

CO CO 


o 
o 


CO 


CO 








CO 


CO 

to 




00 


§ 


s 


s 


§ 


o 

CO 


o 

CO 


r-l 

CO 


s 


CO 
CO 


s 


s 


»o 

CO 


CO 


CO 
CD 


CO 


CO 


00 

CO 


00 

CO 


CO 


OS o 

CO l> 


o 

05 




00 


00 


g 


05 


§ 


§ 


CO 


CO 


CO 


s 


s 


3 


CO 


CO 


CO 


§ 


§ 


5 


CD 


00 

CO 


OS 

CO 


o> 

CO 


g 


o 


l> 


l> 


C<l 


c^ c^ 


o 

00 


CO 


CO 


CO 


CO 
CO 


CO 


CO 


CO 


CO 


CO 


CO 

CO 


CO 

CO 


fe 


CO 


CO 


00 

CO 


00 

CO 


OS 
CO 


o 


o 


i> 


l> 






CO 

1> 


CO 


rH 


rH 


rH 


»o to 


o 


CO 
CO 


CO 

CO 


CO 


CO 


00 

CO 


00 
CO 


OS 
CD 


OS 

CO 


§ 


g 


o 


o 


t> 


l> 


l> 






CO 




^ 


lO 


lO 


lO 


CO 


CO 


t> 






00 00 


o 

CO 


o 




i-H 






1> 


CO 


CO 


CO 




^ 










CO 


CO 




I> 


K 


s 


s 


OS 


OS 


OS 


o 

00 


o 

00 


o 

00 


00 00 


o 




CO 


CO 


CO 








00 


00 


00 


00 


00 


OS 


OS 


OS 


OS 


§ 


§ 


00 


00 


00 


00 


00 


C<l 

00 


CO 
00 


CO 


CO 

00 


rH 
00 


r*4 rH 
00 00 


o 

rj5 


§ 


o 
00 


o 

00 


00 


1-« 
00 


00 


00 


00 


00 


c^ 

00 


00 


CO 

00 


CO 
00 


CO 

00 


CO 
00 


CO 
00 


00 


^ 


00 


lO 
00 


>o 
00 


lO 

00 


CO 

00 


CO 
00 


CD 
00 


CO 


CO 

00 

o 

OS 


00 

o 

OS 


00 00 

o o 
OS OS 


o 

CO 


00 


00 


«5 

00 


00 


CO 
00 


CO 

00 


CO 
00 


CO 
00 


CO 
00 


CO 
00 


00 


00 


00 


00 


00 


b* 

00 


00 

00 


00 

00 


00 

00 


00 
00 


§ 


§ 


OS 

00 


OS 
00 


OS 

00 


o 

OS 


o 


o 

Oi 


§ 


i 


o 

05 


o 
o> 


o 


o 

OS 


i-H 

OS 


1-1 
OS 


OS 


OS 


OS 


OS 


OS 


OS 


OS 


C<l 

OS 


OS 


OS 


OS 


OS 


OS 


CO 
OS 


CO 
OS 


CO 
OS 


CO 

OS 


CO 
OS 


CO 
OS 


to CO 
OS OS 


o 




05 


OS 


05 


Oi 


OS 


OS 


OS 


OS 


iO 
OS 


CO 
OS 


CO 
OS 


CO 
OS 


CO 
OS 


CO 

OS 


CO 
OS 


CD 
OS 


CD 
OS 


CO 
OS 


CO 
OS 


CO 

OS 


CO 
OS 


CD 
OS 


CO 

OS 


CO 
OS 


CO 
o 


CD 
O 


OS 


OS OS 


d 

< 


CO 


CO 
CO 


CO 


00 

CO 


CO 


o 


t^ 


c^ 


CO 






CO 




00 


OS 


o 

00 


00 


00 


CO 
00 


00 

00 


o 

OS 


c^ 

OS 


OS 


CO 

OS 


00 
OS 


o 
o 


c^^ 

o 


2 


CO 00 

o o 



204 MECHANICS OF THE HOUSEHOLD 

attains a condition in which its capacity for containing moisture 
is increased. If after being heated to a high degree — and is 
relatively very dry — the air is reduced to its original temperature, 
the amount of moisture will be the same. as was originally con- 
tained. In heating houses with hot air, the seemingly dry con- 
dition is usually due to temperature alone. When a hot-air 
furnace is provided with the customary reservoir for moistening 
the discharged air, it may be made to produce excellent conditions 
of atmospheric humidity. The heated air readily absorbs the 
water evaporated in the furnace from the water reservoir and 
enters the rooms as relatively dry air but containing more mois- 
ture than the outside air; when it has been reduced in temperature 
by mixing with the cooler air of the house, its moisture content 
remains unaltered and at the lower temperature its relative 
humidity is increased. 

Relative. Humidity .^ — Suppose that on a damp day the outside 
temperature is 50^ and that the atmosphere is 90 per cent, 
saturated. The air that comes into the house at this temperature 
and humidity is heated to 70°. The rise of temperature gives 
the air the property of absorbing additional moisture so that the 
relative humidity which was 90 per cent, is now much less. 
From the table relative humidity, will be seen that at 50' 
temperature and 90 per cent, saturation the air contains 3.67 
grains of moisture. When the air is heated to 70°, it still con- 
tains the original amount of moisture but its relative humidity 
has decreased with the change of temperature. It is really the 
amount of moisture present — 3. 67 grains — divided by the amount 
necessary to saturate the air at 70°, which is 8 grains; this gives 
approximately a relative humidity 40 per cent, saturation. 

As the temperature goes lower, less and less moisture is required 

to saturate the air. If saturated air at 0°F., which contains 

0.48 grain of water, is raised to 70°F. — where 8 grains of water is 

required for saturation — the percentage of saturation would be 

0-48 . 

— ^or 6 per cent. 

The Hygrometer. — The instrument most commonly employed 
for determining atmospheric humidity is the hygrometer. 
This appliance is composed of two thermometers mounted in a 
frame with a vessel for holding water. One of the thermometers 



o 



ATMOSPHERIC HUMIDITY 



205 



is intended to register the temperature of the air and is called the 
dry-bulb thermometer. The bulb of the other — the wet-bulb 
thermometer — is covered with a piece of cloth or other porous 
material which is kept saturated with water, absorbed from 
the water holder. The dryness of the air is indicated in the 
wet-bulb thermometer by the decline of temperature due to 
evaporation. 

The rate of evaporation from the wet-bulb covering will vary 
with the humidity and if the air is very dry the wet-bulb thermom- 
eter will register a temperature several degrees 
below that of the other thermometer. If 
the air is saturated with moisture, no evapo- 
ration will take place and the thermometers 
will read alike. The relative humidity of the 
air as indicated by the readings of the ther- 
mometers is taken directly from a humidity 
table. The table is made to suit any condi- 
tion of atmospheric humidity and the deter- 
minations require no calculation. 

Fig. 157 shows the U. S. Weather Bureau 
pattern hygrometer such as is used at the 
weather stations. The wet-bulb thermom- 
eter has a muslin or knitted silk covering 
which dips into a metal water cup as shown 
in the figure. It is important that the 
covering of the wet bulb be kept in good 
condition. The evaporation of the water 
from the covering leaves in the meshes par- 
ticles of solid matter that were held in solu- 
tion in the water. The accumulation of the 
solids ultimately prevent the water from 
thoroughly wetting the wick. 

An observation consists in reading the two thermometers and 
from the difference between the wet-bulb reading and that of the 
dry-bulb, the relative humidity is taken directly from the table. 
To illustrate, suppose that the dry-bulb thermometer reads 60° 
and that the wet-bulb reads 56°. The difference between the 
two readings is 4°. In the table of relative humidity on page 
202, 60° is found in the column headed, Air temp. <, and opposite 




Fig. 15 7.— Hy- 
grometer of U. S. 
Weather Bureau 
type; for determin- 
ing atmospheric 
humidity. 



206 



MECHANICS OF THE HOUSEHOLD 



that number in the column headed 4 is 78, which indicates that 
under the observed conditions the air is 78 per cent, saturated 
with moisture. This table is suited for air temperatures from 
SS'^F. to 80°F. and depressions of the wet-bulb thermometer 
from l°r. to 20°r. The table, therefore, has a range of variations 
which will admit humidity determinations for all ordinary 
conditions. 

The Hygrodeik. — In Fig. 158 is shown a form of hygrometer 
known as a hygrodeik, by means of which atmospheric humidity 
may be determined without the use of the tables. In the figure 

the wet-bulb and dry-bulb ther- 
mometers are easily recognized. 
A glass water bottle W is held 
to the base of the instrument 
by spring clips which permit its 
removal to be filled with water. 
Between the thermometers is a 
diagram chart from which the 
atmospheric humidity is taken. 
An index arm, carrying a mov- 
able pointer P, permits the in- 
strument to be set for any ob- 
served thermometer readings. 

The index is really a graphical 
method of expressing the figures 
given in the table on pages 202- 
203. In the picture the wet- 
bulb thermometer reads 65^ the 
dry-bulb thermometer 77°. To 
determine the relative humidity under these conditions the mov- 
able arm is swung to the left and the pointer P placed on the 
left-hand scale at the line 65°. The arm is then swung to the 
right until the pointer touches the downward curving line begin- 
ning at 77°, the dry-bulb reading. The lower end of the arm H 
now points to the relative humidity, where 52 per cent, is indi- 
cated by the scale at the bottom of the index. 

The same result is obtained from the table of Relative Humid- 
ity. The readings of the thermometers in the figure give a 
difference in temperature of 12°, the dry-bulb thermometer 




Fig. 158. — The hygrodeik A form 
of hygrometer in which relative hu- 
midity is found directly from a dia- 
gram. 



ATMOSPHERIC HUMIDITY 



207 



reads 77°. Referring this data to the humidity table, the 
column marked 12, for the depression of the wet-bulb ther- 
mometer and opposite 77° in the air temperature column, is 
found 53 which indicates the per cent, of saturation. The 
hygrodeik gives further the temperature of the dew-point, on 
the scale to the right; and the absolute humidity may be found 
by following the upward curving line nearest the pointer, at the 
end of which line is given the value in grains 
of moisture per cubic foot. The hygrodeik 
or other instrument of the kind is very largely 
used in places where relative humidity is 
regularly observed by those of limited ex- 
perience, as in school-rooms, auditoriums, 
etc. Such records are not intended to be 
perfectly accurate and the readings of the 
hygrodeik are very well-suited for the 
purpose. 

In using the hygrometer and the hygrodeik 
the instruments are stationary; they are 
usually hung on the wall in a convenient 
location for observation and are placed to 
avoid accidental drafts in order that the 
conditions surrounding the observation may 
be the same at all times. The evaporation 
which takes place from the wet bulb is due 
to natural convection and does not always 
reach the maximum amount. The evapora- gt^^^/ u^^^^w^ath^r 
tion is furthermore influenced by accidental Bureau type; for accu- 
variations and consequently the results can- ^^*^ determination of 

^ ^ atmospheric humidity. 

not be considered exact. 

Under conditions that demand more exact humidity records 
than are obtainable with hygrometer, the psychrometer furnishes 
means of making more accurate observation. The psychrometer 
shown in Fig. 159 is of the form used by the U. S. Weather 
Department. Like the hygrometer, it is composed of a wet- 
bulb and a dry-bulb thermometer but no water cup is attached 
to the instrument for moistening the wick of the wet bulb. When 
ready for use the wick is wet with water before each observation. 

The greater accuracy to be attained by the use of this instru- 




208 



MECHANICS OF THE HOUSEHOLD 



ment is on account of the maximum evaporation which is ob- 
tained from the wet bulb for any atmospheric condition. The 
evaporation which takes place from the wet-bulb thermometer 
in quiet air is not so great as that which occurs if the same air is in 
motion. In moving air, however, there is a certain maximum 
rate beyond which no further evaporation will take place. 

The motion of the air may be produced either by blowing on 
the bulb with a fan or air blast, or by whirling the thermometer. 
With the psychrometer the latter method is used. This instru- 
ment is provided with a handle which is pivoted to the frame 
and about which it is swung to produce a maximum evaporation 
from the wick. When a motion of the air is attained sufficient 

to produce a saturated atmosphere 
about the bulb, the temperature will 
remain constant. 

A velocity of air or the motion of 
the wet-bulb thermometer 10 feet per 
second is that usually taken as the 
rate for observation and the swinging 
is kept up 3 or 4 minutes or until the 
temperature of the wet-bulb thermom- 
eter remains stationarj^. 

Then the temperature of each ther- 
mometer is read and the humidity 
found in the table. Relative humidity 
determinations may be made at temperatures below the freez- 
ing point if sufficient precaution is taken in the observations. 
When the instrument is not in use, it is kept in tlie metallic 
case shown in the picture, to protect it from injury. 

Dial Hygrometers. — Various forms of hygrometers are in use, 
in which a pointer is intended to indicate on a dial the percent- 
age of atmospheric humidity. That shown in Fig. 160 is one of 
the common forms. Instruments of this kind depend for their 
action on the absorptive property of catgut or other materials 
that are sensitive to the moisture changes of the air. 

These instruments give fairly accurate readings in a small 
range for a limited time, but they are apt to go out of adjustment 
from causes that cannot be controlled. Unless they are occasion- 
ally compared with a standard humidity determination, their 




Fig. 160. — Dial hygrometer. 



ATMOSPHERIC HUMIDITY 



209 



readings cannot be relied upon for definite amounts of atmos- 
pheric moisture. 

The Swiss Cottage "Barometer." — Fig. 161 is one of the 
instruments of absorptive class that are sometimes used as 
weather indicators. The images which occupy the openings in 
the cottage are so arranged that with the approach of damp 
weather the man comes outside and at the same time the woman 
moves back into the house. In fair weather the reverse move- 
ment takes place. The figures are mounted on the opposite 
ends of a light stick which is fastened to an upright pillar. The 
movement of the images is caused by the 
change in length of a piece of catgut which 
is secured to the pillar and also to the frame 
of the house. Any change in atmospheric 
humidity causes a contraction or elonga- 
tion of the catgut which moves the pillar 
and with it the images. 

Since storm}^ weather is accompanied 
by a high degree of humidity and fair 
weather is attended with dry atmosphere, 
the movement of the images indicates in 

, ,, -T T 1 i ji Fig. 161. — Swiss cot- 

some degree the weather changes; but the tage'* Barometer." This 
device is not in anv way influenced by device is arranged to 

1 . " , , . , show the condition of 

atmospheric pressure and hence is not a atmospheric humidity 

barometer. ^y *^® movement of the 

.-^ . - -!->. • r» 11 images. It is not really 

Dew -point. —Dew is formed whenever ^ barometer, 
falling temperature of the air passes the 

point where saturation occurs. The reduction of the tempera- 
ture of air raises the relative humidity because of the dimin- 
ished capacity to contain moisture. As the temperature declines 
there will come a point at which the air is saturated and any 
further decrease of temperature will cause supersaturation. At 
this point the moisture will be deposited on the cooler surfaces 
in the form of drops. The temperature at which dew begins 
to form is known as the dew-point. The sweating of cold 
water pipes, the dew that forms on a water glass and other 
relatively cold surfaces is caused by a temperature below the 
dew-point of the air. 

The temperature^ at which dew forms will depend on the 

14 ' 




210 



MECHANICS OF THE HOUSEHOLD 






1^ 


-^ 




2 


— ( 


b8 




^ 


1 


*<r) 


O 




^ 


<o 



H f^^ 





o 


































CO lO 


lO 


00 


00 


1-1 ic 00 




CO 


































lO CM 
1 1 


1 


1 


1 


+ 


O 












































































N. 


o 


CM CO 


CM 


CM 


CO 


Oi ^ ^ 


































CO 

1 


CM 

1 


T 1 


1 


+ 




1-1 1-1 


o 






































































05 


00 


l> 


05 


''i^ 


O rJH 


r^ 


05 


CM 


"^ CO 05 




























1 


CM 

1 


1 


1 


1 


+ + 






T-t 


1-1 iH tH 


o 


































































lO 


tH 


CO 


r^ 


CM 


CM 


»o 


00 o 


CO 


IC 


t^ 


o» 1-1 00 




CO 




















CO 

1 


CM 

1 


1 


1 


1 


+ 




1-1 


tH 


1-1 


r-l 


iH C<l C^l 




o 














Tt< 


lO 


CO 


o 


lO 


tH 


CO 


CO 


00 




CO »0 


!>. 


O) 


1-1 


CO TJ4 CO 




<N 














1 


CM 

1 


1 


1 


1 


1 


+ 






r-t 


1-1 tH 


i-l 


1-1 


CM 


CM CM CM 


^^ 


o 








o 


00 


05 


CM 


h- 


CO 




-^ 


r>. 


o 


CM 


T« 


CO 


00 o 


1-1 


CO 


iO 


CO 00 05 


1 


1-H 








o 


(N 




1-1 


1 


1 


+ 






1-1 




1-1 


tH 


^ CM 


CM 


CM 


CM 


CM CM Cq 


u 










1 


1 


1 


1 












































































o 












































a 

o 

a 




o 


Oi 


o 


rt< 


on 


rfH 


rH 


CO 


CO 


00 




CO 


lO 


r>. 


OJ 


o 


CM CO 


»o 


r^ 


00 


05 1-H CM 


o 


1 


1 


1 


1 


1 


1 


1 


+ 






rH 


r-4 


1-1 


1-1 




CM 


CM CM 


CM 


CM 


CM 


CM 00 00 














































u 


o 












































a» 




O TtH 


05 


»o 


<N 


I-H 


rt< 


r^ 


05 


CM 


T« 


CO 


r^ 


05 




CM 


"^ 


lO l> 


00 


05 




CM Tt< lO 


.£3 


05 


(N i-H 


1 


1 


1 


+ 








^ 




'-' 


^ 




CM 


CM 


CM 


CM CM 


CM 


CM 


CO 


CO CO 00 


^ 




1 1 






















































































3 


o 












































,o 




lO (M 


r-l 


CO 


CO 


00 


1-1 


CO 


Tt< 


CO 


00 


o 




CO 


■* 


CO 


1^ 


.00 o 




CM 


Tt< 


lO CO 00 


h!> 


00 


1 1 


+ 








'-I 










CM 


CM 


CM 


CM 


CM 


CM 


CM CO 


CO 


CO 


CO 


CO 00 00 
















































9 


CO «c 


00 


o 


C<l 


Tt< 


lO 


1^ 


05 


T-l 


CM 


CO 


ID 


CO 


r^ 


05 


O 


1-1 CM 


^ 


lO 


CO 


l> 05 O 


o 

*i 


l> 


+ 






r-l 










CM 


CM 


CM 


CM 


CM 


CM 


CM 


CO 


CO CO 


CO 


CO 


CO 


00 CO "^ 


o 












































f^ 




05 rH 


CO 


lO 


CO 


00 


o 


tH 


CO 


tH 


iO 


CO 


00 


05 


O 




CM 


tH lO 


CO 


1^ 


05 


O ^ CM 


P< 


CD 


tH 










CM 


CM 


CM 


CM 


CM 


CM 


CM 


CM 


CO 


CO 


CO 


00 CO 


CO 


00 


00 


TJ< -?*< '^ 


P 














































o 


^ CO 


r^ 


05 


o 


(M 


CO 


Tt< 


CO 


r^ 


00 


05 


o 




CM 


"* 


lO 


CO l^ 


05 


o 


iH 


CM CO ^ 




lO 








CM 


<N 


CM 


CM 


CM 


CM 


CM 


CM 


CO 


CO 


CO 


CO 


CO 


CO CO 


CO 


"* 


-* 


TfH TH ^ 




o 


00 o 




(M 


Ttl 


\o 


CO 


t^ 


00 


05 




CM 


00 


'^ 


\n 


CO 


1^ 


05 O 




CM 


00 


Tj< lO 1> 




"* 


rH (N 


<N 


(N 


<N 


(N 


Cv) 


CM 


CM 


CM 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


00 "* 


^ 


tP 


Tt< 


rt< T^ Tt< 




^ 


(N CO 


Tt< 


lO 


1^ 


00 


05 


O 




CM 


CO 


^ 


iO 


CO 


00 


05 


o 


iH (M 


CO 


rH 


iC 


CO »> 05 




CO 


(N (N 


(N 


(N 


Cv< 


(N 


CM 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


Tt< 


-* rt< 


Tfl 


Tt< 


rt^ 


Tji rP ^ 




o 


lO CO 


ts. 


00 


05 


o 


^ 


CM 


CO 


TfH 


»o 


r^ 


00 


05 


o 




CM 


CO '* 


»o 


CO 


!^ 


00 05 O 




(N 


<N (N 




(N 


<N 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


^ 


rt< 


■rtl 


T}< T}< 


"^ 


rr" 


TJH 


Tj< ^ lO 




o 


t^ Oi 


o 




(M 


CO 


Tt< 


lO 


CO 


1^ 


00 


Oi 


o 




CM 


CO 


'^ 


lO CO 


N. 


00 


05 


O ^ CM 




""^ 


(N <N 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


TfTrf^ 


■^ 


'^ 


rJH 


rj< ^ 


Tj< 


^ 


'^ 


lO »o O 


?:; "^ 


Tt^ (N 


o 


r^ 


lO 


CO 




Oi 


00 


1^ 


1^ 


CO 


CO 


r^ 


r^ 


00 


O 


CM Tt< 


r^ 


O 


CO 


t^ CM N" 


2 02 


CO l> 


00 


00 


o> 


o 






CM 


CO 


rfi 


lO 


CO 


1^ 


00 


05 




CM CO 


"i^ 


CO 


r^ 


00 O 1-1 


> ft 










CM 


CM 


CM 


CM 


CM 


CM 


CM 


CM 


CM 


CM 


CM 


CO 


CO CO 


CO 


CO 


CO 


00 -^ Tt< 


o o 


o 


o 


o 


o 


o 


o 


o 


o 


O 


o 


o 


o 


O 


O 


o 


O O 


o 


o 


o 


o o o 


ft 

a 












































O i-< 


(N 


CO 


Tt^ 


•o 


CO 


1^ 


00 


05 


o 


^ 


CM 


CO 


Tt< 


iC 


CO 


t^ 00 


05 


o 


^ 


^^t 




CO CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


Tt< 


-«*< 


^ 


^ 


-"^ 


Tt^ 


Ttl 


Tt^ T^ 


'<i< 


lO 


o 


»C iO o 


< 


< 













































ATMOSPHERIC HUMIDITY 



211 





o 




















































Tt4 


CO 


00 


o 


<N 


Tf4 


CO 


00 


o 


r-t 


CO 


lO 


CD 


00 


O 




CO 


Tt< 


CO 


l^ OS O (N CO 


"i^ 




CO 


*"* 








<N 


(N 


(N 


(N 


<N 


CO 


CO 


CO 


CO 


CO 


CO 


'^ 


Tf 


■* 


rJH 


T}H 


rt< Ttt »0 »0 lO 


»o 




O 


















































CO 


05 


1-1 


(N 


-^ 


CO 


00 


O 




CO 


T*4 


CD 


00 


OS 


rH 


(N 


TJH 


lO 


t^ 


00 


O 1-1 (N Tj< lO 


CO 




lO 






(N 


<N 


(N 


<N 


(N 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


Tt4 


-"^ 


^ 


•^ 


^ 


Tl< 


lO »0 lO lO lO 


»o 




o 




















































CO 


*tl 


CO 


00 


05 




<N 


^ 


CD 


r^ 


OS 


o 


<N 


CO 


lO 


CO 


00 


OS 


o 


<N CO T}< CO I> 


00 




rt< 


C^l 


(N 


<N 


<N 


(N 


<N 


CO 


CO 


CO 


CO 


CO 


CO 


r*H 


^ 


^ 


-"^ 


Tt4 


^ 


-^ 


lO 


lO >c »o »o »o 


lO 




O 


















































">* 


CO 


00 


05 




<N 


"^ 


»o 


r^ 


00 


o 


(N 


CO 


rH 


CO 


r^ 


OS 


o 




CO 


Tj) »0 CO 00 OS 


o 




CO 


(N 


(N 


<N 


<N 


CO 


CO 


CO 


CO 


CO 


CO 


rJH 


Tt< 


Tti 


^ 


^ 


Tt< 


^ 


K) 


o 


lO 


lO lO lO lO »o 


CD 




O 


















































00 


05 




(N 


Tt< 


to 


r^ 


00 


o 


1-1 


CO 


-* 


lO 


t^ 


-* 


OS 


1-1 


(N 


CO 


Tt< 


CO t^ 00 OS rH 


(N 




(N 


(N 


(N 


CO 


CO 


CO 


CO 


CO 


CO 


'^ 


'^ 


T*< 


^ 


rt< 


-"ii 


00 


-^ 


lO 


K) 


»o 


lO 


kO lO iO »0 CD 


CO 


c 


O 




<N 


Tt< 


lO 


1^ 


00 


05 


1-H 


(M 


Tf< 


lO 


CD 


00 


OS 


o 


rH 


CO 


rt< 


lO 


CD 


00 OS O 1-4 (N 


"* 


r 


1-4 


CO 


CO 


CO 


CO 


CO 


CO 


CO 


TjH 


-* 


-* 


Tt< 


^ 


^ 


Tt< 


lO 


lO 


lO 


»o 


lO 


iO 


lO lO CO CD CO 


CD 


u 


o 














































i 




Tt» 


»o 


CO 


00 


05 


tH 


(N 


CO 


lO 


CD 


r^ 


00 


o 




c^ 


CO 


lO 


CO 


1^ 


00 


O 1-1 <M CO Tt< 


^ 


d 

tH 


CO 


CO 


CO 


CO 


CO 


^ 


Tt< 


-* 


Tt< 


-<!*< 


'^ 


'^ 


lO 


lO 


lO 


>o 


lO 


o 


lO 


>o 


CD CO CD CD O 


CD 


















































o 














































© 




CO 


00 


a> 


o 


(N 


CO 


Tt< 


CO 


r^ 


00 


OS 


1-1 


c^ 


CO 


'^ 


»o 


r^ 


00 


OS 


o 


1-1 (M rt< »0 CD 


t^ 


•^ 


05 


CO 


CO 


CO 


rt< 


T}< 


Til 


-* 


-^ 


^ 


"* 


"* 


lO 


lO 


lO 


lO 


^ 


o 


lO 


lO 


CD 


CD CD CD CO CO 


CD 


jQ 






























































































3 


o 














































-9 




a 


o 


(M 


CO 


rt< 


lO 


CD 


00 


OS 


o 




CO 


tH 


lO 


CO 


I^ 


00 


o 


1-C 


(N 


CO -«# »o CO r* 


OS 




00 


CO 


-^ 


Tj< 


-* 


Tt< 


Ti< 


"^ 


Tj< 


"* 


lO 


»o 


lO 


lO 


»o 


lO 


to 


lO 


CD 


CD 


CD 


CO CD CD CD CD 


CD 


o 


T-t 


CO 


tH 


U5 


CO 


r^ 


OS 


o 


I-t 


oq 


CO 


Tt< 


CO 


r^ 


00 


OS 


o 




c^ 


tH 


»0 CO t> 00 OS 


O 


d 
o 


t>^ 


'^ 


^ 


'^ 


-^ 


Tt« 


Tt< 


^ 


»o 


^ 


»o 


lO 


lO 


U3 


»o 


»o 


iC 


CD 


CD 


CD 


CD 


CO CD CD CD CD 


l> 


0) 


o 


















































CO 


lO 


CO 


r^ 


00 


Oi 




<N 


CO 


Tt< 


lO 


CO 


r^ 


00 


o 


1-1 


(N 


CO 


rt4 


»o 


CO t^ 00 OS o 


(N 


o 


rt< 


TJH 


^ 


-* 


"^ 


'^ 


lO 


lO 


o 


o 


lO 


io 


lO 


lO 


CO 


CO 


CD 


CO 


CD 


CD 


CD CD CO CD l>. 


l> 
















































o 


CO 


r^ 


00 


05 


o 




<N 


T« 


lO 


CD 


t^ 


00 


OS 


o 


1-1 


<N 


CO 


lO 


CO 


r^ 


00 OS O iH (N 


CO 




lO 


""^ 


'^ 


rh 


-^ 


lO 


»o 


lO 


lO 


lO 


lO 


o 


lO 


iO 


CO 


CD 


CD 


CD 


CD 


CD 


CD 


CD CD l> l> l> 


t^ 




o 


00 


05 


o 




<M 


CO 


-^ 


lO 


CO 


00 


OS 


o 


1— 1 


(M 


CO 


Tt< 


iO 


CO 


1^ 


00 


OS O 1-1 N CO 


lO 




>«*< 


"* 


'^ 


lO 


lO 


lO 


iO 


»o 


o 


lO 


lO 


iO 


CO 


CD 


CO 


CD 


CD 


CD 


CO 


CO 


CD 


CD l^ t^ t^ t^ 


t^ 




o 


















































o 




(N 


CO 


'^ 


»o 


CO 


r^ 


00 


OS 


o 




<N 


CO 


Tt4 


CO 


r^ 


00 


OS 


O 


th (N CO Tj* u:) 


CO 




CO 


lO 


lO 


lO 


lO 


iC 


^ 


lO 


lO 


lO 


lO 


CD 


CD 


CD 


CO 


CD 


CD 


CD 


CD 


CO 


t^ 


t^ t^ t^ t^ i> 


t^ 




o 


















































(N 


CO 


Tf 


lO 


CO 


r^ 


00 


05 


o 




(N 


CO 


'^ 


»o 


CD 


r^ 


00 


OS 


o 




(N CO T^ lO CO 


t^ 




(N 


»o 


o 


lO 


lO 


lO 


lO 


lO 


o 


CO 


CD 


CD 


CD 


CD 


CO 


CO 


CD 


CD 


CD 


t^ 


t^ 


l> t> l> t> t^ 


t^ 




o 


CO 


tH 


lO 


CO 


r^ 


00 


C7i 


o 




CJ 


CO 


tH 


lO 


r^ 


00 


OS 


O 


»H 


CJ 


CO 


TJ4 lO CD t^ 00 


OS 




i-H 


»o 


lO 


lO 


iO 


»o 


lO 


•O 


CD 


CO 


CD 


CD 


CD 


CD 


CD 


CO 


CD 


l^ 


t> 


t^ 


t^ 


t^ t^ l^ t^ t^ 


t^ 




(M 


00 


lO 


(N 


Ol 


r^ 


CO 


lO 


»o 


lO 


CO 


00 


tH 


TtH 


r^ 


(N 


t^ 


CO 


o 


00 


CD O CD t<. 0> 


(N 


CO 


TJH 


CO 


00 


05 




CO 


»o 


1^ 


OS 


1-1 


CO 


CD 


00 


o 


CO 


»o 


00 




CO 


CD OS C^ lO 00 


(N 


TJH 


"^ 


•^ 


TiH 


rtH 


lO 


lO 


lO 


lO 


lO 


CD 


CD 


CO 


CO 


i> 


l> 


l> 


t^ 


00 


00 


00 00 OS OS ^ 


O 


> K 


O 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


o 


O O O O O 


'' 


ft 














































lO 


CO 


r^ 


00 


Oi 


o 


^ 


(N 


CO 


Tt4 


»o 


CO 


t^ 


00 


OS 


o 


^ 


(N 


CO 


^ 


»0 CO t^ 00 OS 


o 


-*-> 


»o 


lO 


lO 


lO 


o 


CO 


CD 


CO 


CD 


CD 


CD 


CD 


CO 


CO 


CD 


t^ 


t^ 


l> 


t^ 


t^ 


t^ t>. t^ t^ t^ 


00 


< 


5 















































212 MECHANICS OF THE HOUSEHOLD 

amount of moisture present in the air, but with a definite humid- 
ity and air pressure it will always occur at the same temperature. 
If the dew-point is above freezing, the dew will form as drops of 
water, but if it is at or slightly below the freezing point, the dew 
will appear as frost. White frost is formed when the dew-point 
is only a few degrees below the freezing point. A Black frost 
occurs when the atmospheric humidity is so low that dew does 
not form until the temperature is much below the freezing point. 

To Determine the Dew-point. — The dew-point may be found 
by a number of methods, usually described in works on physics 
but practical determinations are made with a hygrometer or 
psychrometer and a dew-point table. Accurate determinations 
must be made by the use of the psychrometer; those made by 
the hygrometer are approximate. Suppose the reading of the 
dry-bulb thermometer is 68 and that this is designated as t; 
at the time the wet-bulb temperature is 57 and is called t\ 
The depression of the wet bulb for these temperatures (M') is 
11°. In the dew-point table above is found in the dry-bulb 
column, opposite this number in the column headed 11 — under 
depression of the wet-bulb thermometer — is 49, which is the 
dew-point for the observed conditions. 

As another illustration, suppose the dry bulb of the psychrome- 
ter marks 65° and the wet bulb indicates 56°r.; then 65-56 
equals 9° of the cold produced by evaporation. The dew-point 
is determined in exactly the same way as with the hygrometer. 
Opposite 65, in the dry-bulb column of the dew-point tabk, 
under the column of differences marked 9, is found the dew- 
point for the observed conditions. This is 49° at which tempera- 
ture dew will begin to form. 

Frost Prediction. — The formation of dew is always attended 
with a liberation of heat — the heat of vaporization — which tends 
to check the further decline of temperature. The heat thus 
developed is usually sufficient to prevent the fall of temperature 
beyond a very few degrees, but 'at times when there is little 
moisture in the air the fall of several degrees of temperature is 
necessary before the heat liberated by the forming dew bal- 
ances the heat lost by radiation and the temperature remains 
stationary. 



ATMOSPHERIC HUMIDITY 213 

This condition of things was pointed out many years ago by 
Tyndall, who in his book on ^^Heaf states: ^^The removal for a 
single summer's night of the aqueous vapor which covers England 
would be attended by the destruction of every plant which a 
freezing temperature would kill/' 

The frosts of late spring and early fall which occur at times 
of dry air and cloudless sky are often caused by local conditions 
that are not forecasted by the weather department and often 
may be successfully combated. 

At the time of suspected frost, the temperature of the dew- 
point in relation to the freezing point determines the probability 
of a freezing temperature. If the dew-point occurs at 10° or 
more above the freezing point there will be little danger of a 
killing frost. As the difference in temperature between the dew- 
point and the frost point decreases, the danger of frost increases. 
If the dew-point falls at the freezing point, frost is a certainty. 

In using the table on page 214, the open diagonal line may be 
considered the danger line and any dew-point falling below the 
temperature thus indicated will be considered dangerously near 
the frost point. This table differs from the other dew-point 
table only in the range of temperature. The dew-point is found 
in exactly the same way as before. In the use of the psychrome- 
ter and table as a means of frost prediction it is first necessary 
to make a reading of the wet-bulb and dry-bulb temperature 
described above. The dry-bulb reading is found in the left- 
hand column of the table; then follow the horizontal line opposite 
the figure, till the perpendicular column is reached indicating 
the difference in reading between the dry and wet bulb. The 
number at the meeting will be the temperature of the dew-point. 
For example, suppose the dry bulb stands at 65° and the wet 
bulb at 55°, the difference being 10° and dew-point under these 
conditions will be 47°. 

If the dew-point is 10° or more above the freezing point there 
is no danger of a frost, but if the conditions are such as to give a 
temperature difference less than 10° above the freezing point 
there would be danger. If the dew-point falls below the open 
diagonal line of the table there is danger and that danger in- 
creases as the difference in degrees between the freezing point 
and the dew-point becomes less. 



2U 



MECHANICS OF THE HOUSEHOLD 



As another illustration, suppose that at sunset at the time of 
suspected frost the dry-bulb thermometer read 54 and the 
depression of the wet bulb showed 10°. Referring to the table 
it will be seen that for these conditions the dew-point falls at 33 
which is only 1° above the freezing point. It is highly probable 
that frost would form. 

Dew-poixt Table for Frost Predictiox 
Depression of the wet-bulb thermometer 



Dry- 
bulb 
temp. 


1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 


13 


70 


69 


67 


66 


64 


62 


61 


59 


57 


55 


53 


51 


49 


47 


69 


68 


66 


64 


63 


61 


59 


58 


56 


54 


52 


50 


48 


46 


68 


67 


65 


63 


62 


60 


58 


57 


55 


53 


51 


49 


46 


44 


67 


66 


64 


62 


61 


59 


57 


55 


54 


52 


50 


47 


45 


43 


66 


64 


63 


61 


60 


58 


56 


54 


52 


50 


48 


46 


44 




65 


63 


62 


60 


59 


57 


55 


53 


51 


49 


47 


45 


42 


41 


64 


62 


61 


59 


57 


56 


54 


52 


50 


48 


46 


43 




40 


63 


61 


60 


58 


56 


55 


53 


51 


49 


47 


44 


42 


41 


38 


62 


60 


59 


57 


55 


53 


52 


50 


48 


45 


43 




39 


37 


61 


59 


58 


56 


54 


52 


50 


48 


46 


44 


42 


41 


38 


35 


60 


58 


57 


55 


53 


51 


49 


47 


45 


43 




39 


36 


33 


59 


57 


56 


54 


52 


50 


48 


46 


44 




40 


38 


43 


32 


58 


56 


55 


53 


51 


49 


47 


45 


42 


41 


39 


36 


33 


30 


57 


55 


54 


52 


50 


48 


46 


44 




40 


37 


35 


31 


28 


56 


54 


53 


51 


49 


47 


44 


42 


41 


39 


36 


33 


30 


26 


55 


53 


52 


50 


48 


46 


43 




40 


37 


34 


31 


28 


25 


54 


52 


50 


49 


46 


44 


42 


41 


39 


36 


33 


30 


27 


23 


53 


51 


49 


47 


45 


43 




40 


37 


34 


31 


28 


25 


20 


52 


50 


48 


46 


44 


42 


41 


38 


36 


33 


30 


27 


23 


18 


51 


49 


47 


45 


43 




40 


37 


34 


31 


28 


25 


21 


16 


50 


48 


46 


^^ 


42 


41 


38 


36 


33 


30 


27 


23 


19 


14 


49 


47 


45 


43 




40 


37 


34 


31 


28 


25 


21 


17 


11 


48 


46 


44 


42 


41 


38 


36 


33 


30 


27 


23 


19 


14 


9 


47 


45 


43 




40 


37 


35 


32 


29 


25 


22 


17 


12 


6 


46 


44 


42 


41 


39 


36 


33 


30 


27 


24 


20 


15 


10 


3 


45 


43 




40 


37 


35 


32 


29 


26 


22 


18 


13 


7 


-1 


44 


42 


41 


39 


36 


33 


30 


27 


24 


20 


16 


11 


4 


-5 






40 


37 


35 


32 


29 


26 


23 


19 


14 


8 


1 


-9 


43 


41 


39 


36 


34 


31 


28 


25 


21 


17 


12 


6 


-2 


-15 


42 


40 


38 


35 


33 


29 


26 


23 


19 


15 


9 


3 


-6 


-22 


41 


39 


36 


34 


31 


28 


25 


22 


17 


13 


7 





-11 


-32 


40 


38 


35 


33 


30 


27 


24 


20 


16 


11 


4 


-4 


-16 


-74 


39 


37 


34 


32 


29 


26 


22 


18 


14 


8 


2 


-8 


23 




38 


36 


33 


31 


28 


24 


21 


17 


12 


-6 


-1 


-12 


-35 





ATMOSPHERIC HUMIDITY 215 

Prevention of Frost.— From the discussion of frost formation 
it is evident that, the temperature of the dew-point being the 
determining factor in its probable occurrence, any expedient that 
may be used either to increase the humidity or to conserve the 
radiation of heat would prevent a dangerous decline of tempera- 
ture. Frost prevention is practised in all fruit-growing regions 
and the method pursued depends on the kind of vegetation to 
be protected. 

In the protection of orchards the use of smudge pots are prob- 
ably the commonest means for preventing the loss of heat. 
The object is to create a cloud of smoke over and about the 
orchard so that it forms a protective covering which prevents 
the escape of the heat. 

In the case of a light frost — that is, where the temperature 
falls only a few degrees below the frost point — the plants in small 
gardens and flower beds may be prevented from freezing by 
liberal sprinkling with water. This is done to raise the humidity 
of the atmosphere surrounding the vegetation. Most vegetation 
withstands the temperature at the freezing point without particu- 
lar injury, and the freezing of part of the water liberates heat in 
sufficient quantity to prevent a further decline of temperature. 
This heat liberated on the freezing of water is described in physics 
as the heat of fusion and in changing part of the water into ice 
sufficient heat is liberated to check the further fall of temperature. 

Humidifying Apparatus. — Opportunity for adding moisture, 
in the desired quantity, to the air of the average dwelling is 
limited to the evaporation of water in the heating plant, from 
vessels attached to the radiators or that which goes on in the 
kitchen. Household humidifying plants are within the range 
of possibility but there is not yet sufficient demand for their 
use to make attractive their manufacture. 

In the hot-air furnace a water reservoir is usually a part of the 
chamber in which the air supply is heated. The water in the 
reservoir is heated to a greater or lesser degree, depending on the 
temperature of the furnace and vaporized both by heat and by 
the constantly changing air. 

In the use of a steam plant or hot-water heating plant the 
opportunity of humidifying the air is very limited. One method 
is that of suspending water tanks to the back of the radiators 



216 MECHANICS OF THE HOUSEHOLD 

from which water is vaporized. While this method is fairly 
efficient as a humidifier it is inconvenient and therefore apt to be 
neglected. In houses heated by stoves there are sometimes 
water urns attached to the top of the frame which are intended 
for the evaporation of water but as a rule they are not of sufficient 
size to be of appreciable value. 

The quantity of water required to humidify the air of a house 
will depend firsts on the temperature and humidity of the out- 
side air; second, on the cubic contents of the building; third , 
on the rate of change of air in the building. If the ventilation 
is good the rate of atmospheric change is rapid and the amount 
of water in consequence must be correspondingly increased. 

The data included in the following table showing the relative 
humidity and amount of water required were taken from a seven- 
room frame dwelling in Fargo, N. D., during particularly severe 
winter weather. The relative humidity determinations were 
made with a hygrodeik each day at noon. The house was heated 
by a hot-air furnace arranged to take its air supply from the 
outside. 

The air supply is recorded under Cold-air intake. The furnace 
was provided with a water pan for humidifying the air supply. 
The amount of water evaporated each day is recorded in the col- 
umn headed Evap. in 24 hours. The outside temperature 
ranged from — 12°F. to — 21°r. The weather was clear and calm 
except the last day, Jan. 12, which was windy. The higher 
humidity on that day was no doubt due to the greater amount 
of heat required from the furnace and the consequent evaporation 
of the water from the water pan. 

The humidity determinations made by a hydrodeik, as before 
explained, are only approximately correct but sufficiently exact 
for practical purposes. The temperature is given in degrees 
Fahrenheit. 

In the table it will be noticed that the outside air was used 
only a part of the time because of the severity of the weather. 
Attention is called to the quantity of water required to keep the 
humidity at the amount shown. This averages 27)^ quarts 
per day. At the time these observations were made the physics 
lecture-room at the North Dakota Agricultural College averaged 
18 to 20 per cent, saturation during class hours, with observations 



ATMOSPHERIC HUMIDITY 



217 



made from a similar instrument. This is a steam-heated room 
with only accidental means of adding water to the air. The 
result was an atmosphere 33-^ per cent, above that of Death 
Valley. 

Hot-air Furnace 
Readings taken at 12 o'clock , noon each day 



Date 


Temp, 
outside 


Wet 
bulb 


Dry 

bulb 


Per 
cent, 
satu- 
rated 


Evap. In 

24 hours 

quarts pints 


Cold-air intake 


Dec. 13 

Dec. 14 

Dec. 15 

Dec. 16 

Dec. 17 

Dec. 18 

Dec. 19 

Dec. 20 

Jan. 8 

Jan. 9 

Jan. 10 

Jan. 11 

Jan. 12 


-13 
-18 
-20 
-18 
-22 
-16 
-10 

-12 
-17 
-16 
-21 
-15 


54° 
55 
57 
57 

58 
55 
57 
59 

58 
57 
58 
60 
60 


63° 

66 

68 

67 

69 

65 

68 

70 

71 

71 

69 

75 

73 


53 
47 
49 
51 
48 
51 
47 
49 
43 
39 
45 
40 
46 


21 

20 1 

18 1 

17 m 

20 1 

13 K 

18 

25 

27 1 

30 

30 


Closed 8 a.m. 

Open 

Closed 7 a.m. 

Closed 7 a.m. 

Closed 7 a.m. 

Closed 6:30 a.m. 

Closed 8 a.m. 

Not open at night 

Closed 

Open 24 hours 

Open 10 hours 

Closed 

Closed 



The amounts of water evaporated may seem large to those 
who are unaccustomed to quantitatively consider problems in 
ventilation but the small amount of water in the air at —21° 
must produce a very dry atmosphere when it is raised to 70° in 
temperature. 

The amount of moisture in air at 20°F. and at 80 per cent, 
humidity is only 1.58 grains to the cubic foot. If this air is 
now raised to 70° the moisture will still be 1.58 grains where 
there should be 4 grains of water to make 50 per cent, humid- 
ity. It therefore will require the addition of practically 2.42 
grains of water for each cubic foot of entering air in order to 
bring it up to 50 per cent, humidity. 

In a case with the above conditions of atmosphere, suppose 
it is desired to know the amount of water that would be taken 
up in humidifying the air for a school-room of size to accommodate 
40 pupils. The prescribed quantity of air for this purpose is 



218 MECHANICS OF THE HOUSEHOLD 

30 cubic feet per minute for each pupil. The air is to be main- 
tained at a humidity 50 per cent, saturated. The problem will 
be one of simple arithmetic. If each pupil is to receive 30 cubic 
feet of air per minute or 1800 cubic feet per hour, the 40 pupils 
receiving 1800 cubic feet per hour will require 40 X 1800 = 72,000 
cubic feet of air per hour. To each cubic foot of the air is to be 
added 2.74 grains of water, 72,000 X 2.42 = 164,240 grains of 
water. Reducing this to pounds, 164,240 -r- 7000 = 23.46 
pounds or 2.77 gallons of water per hour. 

In practice the room will show a higher amount than 50 per 
cent, humidity with this addition of the amount of water, because 
of the water vapor that is exhaled from the lungs of the pupils. 
That a considerable amount of water vapor is added to the atmos- 
phere by breath exhalation is made evident from the moisture 
condensed by breathing on a cold pane of glass. In any unven- 
tilated room occupied by a considerable number of people the 
humidity is thus increased a very noticeable amount. 

The change in humidity of the air in a closed room filled with 
people is very pronounced. The constant exhalation of moisture 
from the lungs is sufficient to saturate the air in a short time. 
The heavy atmosphere of overcrowded, unventilated rooms is 
due to moisture exhalation, body odors and increased carbonic 
acid gas. As the humidity of the atmosphere is increased a 
sensation of uncomfortable warmth is the result of the lesser 
evaporation. 



CHAPTER XI 
VENTILATION 

The purity of air in any habitable enclosure is determined by 
the amount of CO2 (Carbonic acid gas) included in its composi- 
tion. The process of ventilation is that of adding fresh air to 
the impure atmosphere of houses, until a desirable quality is 
attained. In the opinion of hygienists, when air does not exceed 
6 to 8 parts of CO2, by volume in 10,000, the ventilation is desir- 
able. Ordinary outdoor air contains about 4 parts of CO2 to 
10,000, while very bad air may contain as high as 80 parts to the 
same quantity. The quantity of air required for the ventilation 
of a building is determined by the number of people to be pro- 
vided. The amount of air required per individual per hour 
necessary to produce a desired condition of ventilation is deter- 
mined by adopting a standard of purity to suit the prevaihng 
circumstances. 

In hospitals where pure air is considered of greatest impor- 
tance 4000 and 5000 cubic feet per inmate per hour is not uncom- 
mon. The practice of supplying 30 cubic feet of air per person 
per minute (1800 cubic feet per hour) seems to fulfill the average 
requirements. It is the amount commonly specified for 
school-rooms. 

The quantity of fresh air required per person to insure good 
ventilation will depend on the type of building to be supplied 
and varies somewhat with different authorities. The De Chau- 
mont standard is that of 1 cubic foot of air per second or 3600 
cubic feet per hour, for each person to be accommodated. De 
Chaumont assumed a condition of purity which will permit less 
than 2 parts in 10,000 of CO2 over that carried by country air. 
In considering the same problem from the basis of permissible 
CO2, if 6 parts of CO2 in 10,000 represents purity of the required 
air, then 3000 cubic feet per person per hour is necessary. Like- 
wise, the varying amounts for different degrees of purity are 

219 



220 



MECHANICS OF THE HOUSEHOLD 



given by Kent in the following table. The upper line gives the 
permissible number of parts of CO2 per 10,000; while below each 
factor appears the number of cubic feet of air required per hour 
for each person supplied. 



6 


7 


8 


9 


10 


15 


20 


= Parts of CO2 per 10,000 


3,000 


2,000 


1,500 


1,200 


1,000 


545 


375 


= Cubic feet or pure air 
per hour 



It is generally recognized, that it is possible to live under 
conditions where no attempt is made to change the air in a build- 
ing. It is also an established fact that the only preventive and 
cure for tuberculosis is that of living constantly in an atmosphere 
of the purest air. The greatest attainable degree of health is 
enjoyed by those who live in the open air, because oxidation 
is one of the most efficient forms of prevention and elimin ation 
of disease, and an abundance of pure air is the only assured 
means of sufficient oxidation. 

The De Chaumont standard is intended to represent the limit 
beyond which the sense of smell fails to detect body odors or 
'^closeness'' in an occupied room. The amount of CO^that air 
contains is not an absolute index of its purity, but it gives a 
standard under ordinary conditions, makes possible the require- 
ment of a definite quantity of air. If it were possible to express 
the amount of oxygen contained in the atmosphere, the same 
relative condition might be attained. 

The ordinary man exhales 0.6 cubic foot of CO2 per hour. 
Some forms of lighting apparatus produces this gas in greater 
amounts. The ordinary kerosene lamp gives out 1 cubic foot of 
CO2 per hour. A gas light using 5 cubic feet of gas per hour 
produces 3.75 cubic feet of CO2 in the same time. Any form 
of combustion permitting the products to escape into the air 
of the room tends to lower the quality of the atmosphere by add- 
ing to its content of CO2. 

The prevailing impression that impure air is heavy and settles 
to the floor is erroneous. Impurities in the form of gases and 
vapors (principally carbonic acid gas and odors) diffuse through- 



VENTILATION 221 

out the entire space, and the entering fresh air tends to dilute 
the entite volume. 

As a quantative problem, ventilation consists in admitting 
pure air into an impure atmosphere in amount to give a definite 
degree of purity. This is accomplished by admitting sufficient 
air to completely change the atmosphere at stated intervals, or 
to provide a definite quantity for each inhabitant. 

The methods by which ventilation may be accomplished will 
depend on the type of building to be ventilated and the apparatus 
it is possible to use. When the use of mechanical ventilation 
appliances are permissible, any desired degree of atmospheric 
purity may be maintained at all times, under any condition of 
climate or change of weather. 

In buildings where mechanical ventilation cannot be considered 
as that of the average dwelling, the problem is one of producing 
an average condition of reasonably pure air by natural convec- 
tion. In the average dwelling, ventilation is accomplished by 
the natural draft produced in chimneys or air flues, by partially 
opened windows and by the force produced by the movement of 
the outside air. In some buildings a better condition of ventila- 
tion is attained by ordinary means than at first sight seems 
possible. 

The fact that it is difficult to keep a house at the desired tem- 
perature during cold weather indicates that a considerable 
quantity of outside air is constantly entering and heated air is 
leaving the building. It may be, however, that the ventila- 
tion under such condition is unsatisfactory, even though the 
amount of air which enters the building is sufficient in quantity 
to produce a desirable atmosphere. If the places of entrance 
and exit are so located that the entering air has no opportunity 
to mix with the air of the building, the advantage of its presence 
is lost. 

In the burning of fuel in stoves and furnaces, the amount of 
oxygen necessary for combustion is supplied by the air which is 
first taken into the house and thus forms its atmosphere before 
it can enter the heater. Theoretically, about 12 pounds of air are 
required for the combustion of a pound of coal, but in practice 
a much larger amount actually passes through the heater. As 
given by Suplee, from 18 to 24 pounds of air are actually used 



222 



MECHANICS OF THE HOUSEHOLD 



in burning 1 pound of coal. If 20 pounds of air per pound of fuel 
is taken as an average, there will be required 198 cubic feet of 
air per pound of coal consumed. In a building that requires 10 
tons of coal to be used during the winter months, this would 
necessitate the average use of 1977 cubic feet of air per hour, 
which must be drawn into the house before it can enter the stoves. 
This air acts as a means of ventilation and if it is used to advan- 
tage would furnish a supply sufficient in amount to produce 
excellent ventilation, considerably more than enough for two 
people. The amount of air drawn into the house in this way is 
further increased by that which passes into the chimney flue 
through the check-draft dampers, when the 
fires are burning low. 

The aim of architects is to construct 
buildings as completely windproof as possi- 
ble, but that such construction is attained 
in only a slight degree is sometimes very 
evident during cold weather. No matter 
how tightly constructed buildings may be, 
most of the contained air filters through the 
cracks and crevices of the walls or through 
the joints of the windows and door frames, 
because there is seldom any special provision 

Fig. 162. — A simple ^ c - , , t^ • . i 

expedient for the pre- made for its entrance. Durmg extremely 
vention of drafts and cold and windy weather the amount of air 

improving ventilation. ,, , , ii i • • ii • i 

that enters the house m this way — because 
of the air pressure on the windward side — is sometimes sufficient 
to keep the temperature at an uncomfortably low degree. Under 
such conditions, the air drifts through the building faster than 
it can be raised to the desired temperature and the rooms on the 
windward side of the building cannot be kept comfortably warm. 
The common method of ventilation in dwellings is that of 
partially open windows. The air thus admitted, being colder 
and consequently heavier than that at the temperature of the 
room, sinks to the lowest level. In so doing it creates drafts 
that produce discomfort and act only in the smallest degree to 
produce the desired effect of ventilation. The effect of window 
ventilation may be greatly improved by a simple expedient 
illustrated in Fig. 162. In this, the entering air meets a deflector 




VENTILATION 



223 



in the form of a board or pane of glass that directs the cold air 
upward where it mingles with the heated air with the least pro- 
duction of a noticeable draft. This is the most efficient method 
of house ventilating where no special provision is made for the 
admission of fresh air. 

The object sought in ventilating a room is to keep up the 
quality of the air by constant addition of fresh air, and in order 
to bring about a uniform purification of the entire atmosphere 
the entering air must be mixed with that already in the enclosure. 



A BC 




Fig. 163. — A chimney flue used as a ventilator. 

If the discomforts of drafts are to be avoided, this mixing proc- 
ess must be brought about by admitting the cold air at the 
upper part of the room. 

Warm air rises to the top of the room because it is lighter than 
the colder air beneath it. The coldest air is always lowest in 
point of elevation and unless there is some means to stir up the 
entire volume this condition will always remain the same. 

When the easiest means of air for entering and leaving are near 
the floor, the cold entering air and that which goes out will 
always be in the lower part of the room, even when the supply 



224 



MECHANICS OF THE HOUSEHOLD 



is amply large. If no opportunity is given for the fresh air to 
mix with that already in the room, a poor average quality will 
result. 

In the process of ventilation, the entering air should be admit- 
ted at, or directed toward, the highest part of the room, so that 
the pure cold air may have a chance to mix with that which is 
warmest. Air is not a good conductor of heat, and in mixing 
warm and cold air the cold particles will tend to float downward 




Fig. 164.- 



-Method of admitting cold air into rooms so as to produce the best 
condition of ventilation. 



and take up heat from the warmer air with which it comes into 
contact, and thus produces a more uniform temperature. 

The condition most to be desired is that of admitting cold 
air at a point where it will most readily mingle with the warm 
air from the source of heat. The reduction in temperature that 
must take place from this mixture will produce a gravitational 
circulation. Unfortunately this is not always possible to attain 
in an old building, but in the construction of a new building air 



VENTILATION 225 

ducts placed to admit air at points near the ceiling and located 
with reference to the supply of heat will bring about the best 
effect of ventilation. 

The air which enters a room should, therefore, be near the 
top or so directed that the entering shaft will carry it upward. 
The air which is taken out of the room should leave from a point 
near the floor. In so doing it will tend to produce a more uniform 
quality and a more even distributor of the heat. 

In order that the most desirable quality of atmosphere may 
be attained, there should be a constant supply of pure air enter- 
ing and an equal amount discharging from the house. In the 
better-constructed dwelling such a condition is often provided 
through a ventilating flue that is a part of the chimney. This 
flue is arranged with registers placed to take air from the parts 
of the house requiring the greatest amount of air. Such an 
•arrangement is shown in the picture in Fig. 163. 

Fig. 164 shows the method of Fig. 163 combined with a 
direct means of admitting fresh air from the inside. The fresh 
air ducts should be provided with dampers to control the effect 
of extreme cold and wind. 

Quantity of Air Discharged by a Flue. — Any change of tem- 
perature of air produces a change equal to 3^^ 91 part of its 
volume, for each degree yariation. If a cubic foot of air is raised 
in temperature 1°F., its volume is 3^^9i part larger than the 
original volume, and its buoyancy in the surrounding air is 
increased correspondingly. Air that has a temperature higher 
than that surrounding it will tend to rise because it is lighter. 
The air rising from a hot-air register or from a heated surface 
are illustrations of this condition. 

Since the change of volume — or what is the same thing, its 
tendency to rise — increases 3^^ 91 for each degree difference in 
temperature, the upward velocity of highly heated air will be 
very great. In warm air that fills a chimney flue or a room, the 
same tendency exists, the warmest air rises to the highest point 
and if the air can escape, as in the case of a chimney, a draft will 
result. 

The draft of a chimney, in quiet air, is due to the difference in 
temperature between the air inside the flue above that outside the 
house. A chimney that does not ^^draw^^ and causes a stove to 

15 



226 MECHANICS OF THE HOUSEHOLD 

'^smoke/^ will often produce sufficient draft after the flue 
has been warmed. The upward movement of the warmer air 
in the flue produces a constantly increasing velocity, until it 
reaches the top of the chimney. This is an accelerated velocity 
that may be calculated by use of the formula given in physics, 
to express the velocity of accelerated motion. The well-known 
formula V=\/2gh may be modified to express the conditions 
existing in a flue and permit of the calculation of the quantity 
of air discharged. 

The upward flow of air in a chimney flue being due to the 
difference in temperature of the air in the flue over the outside 
air, the flow of air from the rooms will continue as long as the 
difference in temperature exists. Moreover, the air that is 
discharged from the rooms will be replenished from the outside, 
and for the air sent out of the flue a corresponding amount will 
be brought into the rooms through any openings that exist — door 
or windows or through cracks or crevices, depending on the 
completeness with which the house is closed. In no case is a 
house air-tight. The air pressure registered by the barometer is 
always the same inside as that outside the building. During 
cold weather, when the windows and doors are closed, the air is 
escaping through the chimney and also through every little 
crack and chink in the top of the rooms where the air is warmest. 
The colder air is entering at the same time through the joints 
about windows, door casings, through the crevices in the walls 
and particularly through the open joints made by the baseboards 
and the floor. This latter entrance of cold air is one of the com- 
monest causes of cold floors. The shrinkage of the baseboards 
and floors from the quarter-round moulding which forms the 
joint leaves openings through which cold air is freely admitted 
from partitions and outside walls. The cold, heavier air remains 
near the floor because it can rise only when heated or forced 
upward by a draft. If the same air were permitted to enter at 
points near the ceiling and mingle with the warmest air in the 
room, a more uniform temperature would result, as well as 
better ventilation. The entering cold air, mixing with the 
warm air at the top of the room, would be reduced in its tem- 
perature and weight. The heavier air in falling would diffuse 



VENTILATION 227 

with the air beneath it and thus improve the general quaHty of 
the atmosphere. 

It is important to remember that the discharge of air through 
a chimney flue will depend, in considerable amount, on the rate 
the new air is able to enter the house. In a new, tightly con- 
structed house, the flue is often capable of discharging air much 
faster than it can enter, when it must find its way in through 
accidental openings. In such cases an open door or window im- 
mediately improves the draft of the stove. 

The ventilation in the average dwelling is and must be ac- 
complished by natural draft that is generated through difference 
in temperature of the air. The possibility of providing an 
acceptable system of continuous ventilation is confined to the 
draft of the chimney or to a flue provided especially for that 
purpose. Such being the case, the dimensions of flues con- 
structed for ventilation should be the subject of investigation. 
The work that a chimney or ventilating flue has to do is con- 
tinuous and will last throughout its lifetime; its proportions 
should therefore be considered with more than passing care. 

It has been stated that the method of calculating volumes of 
air that will pass through a flue is based on the formula used to 
express the velocity of accelerated motion. The fundamental 
formula must be changed to suit the conditions produced when 
air is heated and made buoyant by expansion. 

As has been stated, the change in temperature of air 1°F. 
causes an increase or decrease 3^^9i part of its volume for each 
degree change. Any portion of air, warmer than that which 
surrounds it, tends to rise because of its lighter weight; the tend- 
ency to rise increases with the difference in temperature. The 
draft of a flue is caused by this condition of difference in tempera- 
ture between the air inside the flue and the outside atmosphere. 

In order that this general condition may be expressed in the 
simplest form let: 7" = the temperature inside the flue in de- 
grees F. 

t = the temperature outside the flue in degrees F. 
H = the height of the flue in feet. 

T — t 
The quantity aq^ expresses the difference in temperature in 

degrees, divided by the change of volume for each degree. This 



228 MECHANICS OF THE HOUSEHOLD 

gives the constant upward tendency of the air in passing through 
the flue. If this quantity is placed in the formula V = \/2gh, 
so as to exert its influence through the height of flue H, the con- 
dition may be expressed: 



= ^2^^ 



V = J2a^H 



The factor g^ representing the acceleration of gravity, is 
constant and equal to 32 feet per second. The quantity 2g 
may be removed from under the radical and the formula becomes : 



= 8^ 



^-'h 



491 



The formula may now be used to express the volume of dis- 
charge of air from a flue. Suppose such a flue contains an area 
of 1 square foot in cross-section and that it is desired to estimate 
the air discharged from the flue per hour. The value of g is given 
in feet per second, and in order to make the formula express the 
volume of air discharged in cubic feet per hour, it must be 
multiplied by the number of seconds in an hour. Volume 
discharged in cubic feet per hour 



= 60 X 60 X 8iJ^Qj-^ H = 28,800 ^^^ H 

This formula applies to conditions such as will permit uniform 
movement of the air in a straight flue, uninfluenced by irregular, 
odd-shaped passages and rough surfaces. Moreover, it is 
supposed that the air may enter the house as rapidly as it escapes. 
The theoretical discharge will, in most instances, be less than the 
calculated amount, because the air cannot enter the house as 
fast as it may be discharged by the flue. It is a common custom 
to consider the theoretical flue only 50 per cent, efficient. As 
applied to the formula, the constant 28,800 when reduced 50 per 
cent, will become 14,400, and will be so used in the calculations 
as follows. 

As an illustration of the application of the formula, suppose 
that the temperature in the house and in the flue is 70°F. and that 
the outside temperature is 20°F. The height of the chimney is 
30 feet. The area of the flue is 1 square foot. Volume = 14,400 



VENTILATION 



229 



VT — t /70 — 20 

-^gj- H = 14,400 \-^Q^ X 30 = 25,140 cubic feet per hour. 

Such a ventilating flue would be sufficient in size, under the 
conditions given, to furnish air at the rate of 25,140 cubic feet 
per hour or 30 cubic feet per minute to 13 persons, provided of 
course that the air could enter the building at the rate demanded. 
Where no provision is made for the air to enter the building 
it must find its way by the accidental openings. A common 
illustration of this effect may be noticed in the rate at which the 
fire of a stove will burn in a tightly closed room. The opening 
of a door or window causes an immediate increase of combustion, 
because of the extra air supply. It is evident that in well- 
constructed houses other means should be provided for admitting 
air than that of accidental opening. 

The following table calculated by the above formula gives the 
quantity of air in cubic feet per hour discharged through a flue 
of 1 square foot cross-section. The table shows the calculated 
discharge from flues of heights varying from 15 to 40 feet, and 
with temperature differences from 10° to 100° between the out- 
side air and that of the house. 



Height of flue 


Temperature of air in the flue above that of external air 


in feet 


10 


15 


20 


25 


30 


50 


100 


15 


7,980 


9,720 


11,280 


12,550 


13,800 


17,820 


25,140 


20 


9,180 


11,180 


13,080 


14,520 


15,900 


20,520 


29,040 


25 


10,260 


12,600 


14,520 


16,260 


17,820 


22,980 


32,460 


30 


11,280 


13,800 


15,900 


17,825 


19,500 


25,140 


35,580 


35 


12,180 


14,880 


17,160 


19,200 


21,060 


27,180 


38,400 


40 


13,020 


15,900 


18,360 


20,520 


22,500 


29,040 


40,980 



In Fig. 163 is illustrated the form of chimney that is often used 
for the ventilation of dwellings. This is built with three flues. 
The flue to the left — marked A at the top — is intended to carry 
away the smoke and gases from the kitchen range. The flue 



230 MECHANICS OF THE HOUSEHOLD 

to the right is that to which is connected the smoke pipe from the 
furnace. The flue in the middle marked B is for ventilation. 
Occupying as it does the space between the other two, it is kept 
warm by the heat of the other flues and the draft is thus increased. 
Openings to the flue are shown in the different floors at the points 
R and S. The openings are furnished with registers which may 
be regulated to suit the weather conditions. 

The dimensions of such a flue may be calculated by the formula 
given or the area may be taken from the table to correspond 
with required conditions. In all cases flues should be made 
ample in size, as they must often do their maximum work under 
the poorest conditions for the production of good draft. 

The amount of air discharged from the flue as given in the 
table is due to the gravitational effect alone. The suction 
produced by the wind adds in a very large degree to the amount 
of air discharged. The quantity of air that will flow from a 
30-foot flue, by reason of the suction of the wind, blowing 7 miles 
per hour is equal to the same flue working by gravity with a 
temperature difference of 20°. With a wind velocity of 7 miles 
per hour and a temperature as given, the capacity of the flue is 
doubled. It is easy, therefore, to understand why the rate at 
which fires burn is so greatly increased by high winds. At the 
time of very high winds, a chimney flue will carry away three 
and even four times the volume discharged at the time of atmos- 
pheric calm. 

Cost of Ventilation. — The cost of good ventilation is often 
looked upon as prohibitive, because of the expense in heat neces- 
sary to keep the inside atmosphere at standard purity. Cost of 
ventilation is determined by analysis of the known conditions and 
calculations made of the amount of extra heat necessary to 
warm the greater volume of air. 

The common practice of estimating the quantity of heat used 
in any form of heating or ventilation is by reference to the B.t.u. 
used in producing the desired condition. This unit, as has al- 
ready been stated, is the amount of heat necessary to change a 
pound of water, 1°F. 

In considering the cost of heating the air for ventilation, it 
must be borne in mind that the heat used in raising the tempera- 
ture of the air contained in an enclosure is only a part of that 



VENTILATION 231 

necessary for warming the building. Most of the heat used goes 
to keep up the loss due to radiation and conduction which goes 
on from the windows, the walls and other parts of the building 
that are exposed to the outside cold. The material of which 
the building is composed must be heated and in turn radiates 
its heat to the colder outside air. 

The quantity of heat necessary to change the temperature of 
a definite amount of air is easy of calculation. The problem 
is that of determining the number of heat units required to 
warm the necessary air to suit the average condition of weather. 
We will assume that the house is heated to the normal tempera- 
ture 70°, and that the additional cost of heating the air for ven- 
tilation over the amount thus expended is the cost of ventilation. 

Assuming that the house is so constructed that it is possible 
to supply air at the rate of 1000 cubic feet per hour to each 
person of a family of five, this condition will necessitate 5000 
cubic feet of air per hour or 120,000 cubic feet of air per day. 

The house is such that 10 tons of coal are required per year, 
at a cost of $10 per ton. The period of winter weather will be 
considered 5 months of 30 days each. This will be 150 days, 
during which the fuel for heating the house will cost 66% cents 
per day. 

The average temperature of the outdoor air during the entire 
period will be assumed to be 20°F., thus requiring the air for 
ventilation to be changed 50° in order to raise it to the normal 
temperature, 70°. 

The weight of a cubic foot of air at 70° is practically 0.075 
pound. The 120,000 cubic feet of air used per day will, therefore, 
weigh 0.075 X 120,000 = 9000 pounds which must be raised 
50° in temperature. 

In order to express in B.t.u. the necessary heat required to 
produce the change of air temperature, the quantity of air is 
best stated in an equivalent amount of water. The specific 
heat of air is 0.237; that is, the amount of heat necessary to 
change a pound of air 1° is 0.237 of the amount used in changing 
1 pound of water 1°. The 9000 pounds of air (expressed as an 
equivalent amount of water will then be: 

9000 X 0.237 = 2133 pounds of water. 



232 MECHANICS OF THE HOUSEHOLD 

This amount of water raised 1° is equivalent to raising 120,000 
cubic feet of air 1°. Now the average change in the temperature 
of the air is 50°, so that 50 X 2133 will be the number of heat 
units used. 

50 X 2133 = 106,650 B.t.u. 

That is, 106,650 B.t.u. will be required to heat the air for 
ventilation one day. 

In order to express this amount of heat in terms of fuel con- 
sumed, it will be assumed that the coal contained 14,000 B.t.u. 
per pound, this being a fair valuation of good coal. The average 
house-heating furnace will turn into available heat about 50 
per cent, of the fuel burned. This value is taken from house- 
heating fuel tests made at the Iowa State College. The avail- 
able heat in each pound of coal then will be 7000 B.t.u. 

106,650 ^ 7000 = 15.2 pounds of coal. 

That is, 15.2 pounds of coal per day must be burned in order 
to furnish 1000 cubic feet of air per person each hour at the 
desired temperature. 

At $10 a ton of 2000 pounds, the fuel costs 3-^ cent per pound. 
The cost of ventilation is, therefore, y^ X15.2 = 7.60 cents a 
day, not an extravagant amount for good air. 

It is evident that with the use of hot-air furnaces which take 
their entire amount of air from outdoors, the extra amount of 
heat necessary for this improved quality of atmosphere is very 
well expended. The use of ventilating devices adds only a 
relatively small amount to the total cost of heating and provides 
for the well-being of the occupants of the house — in the form of 
good air — an amount of healthfulness impossible of calculation. 

The best ventilation is attained where a constant supply of 
fresh air is admitted to the house at points from which the best 
circulation may be secured and equal quantities of vitiated air 
are removed from the different apartments. 

It is understood that in the process of natural ventilation the 
desired condition can only be approximated and that the per- 
missible ventilation appliances are so placed as to give results 
such as to permit the air to follow the natural laws that must 
prevail. 



VENTILATION 



233 



If the house is heated by stoves, the outside air is best admitted 
near the ceiUng, so that the cold air on entering may come into 
contact and mingle with the warmest air in the room. The 
circulation will by this method be effected by gravity. 

In the use of the hot-air furnace, the air supply — as has already 
been explained in the figures on pages 55 and 58 — is brought 
from the outside, where after being heated it enters the rooms 
through the registers placed near the floor. Being 
warmer than the air in the room, it tends to 
quickly rise. The currents set up by its motion 
help to produce a uniform temperature and to 
diffuse the new air through the entire space. The 
more evenly the air is distributed the more uni- 
form will be the condition of temperature of the 
room. 

In hot-water and steam heating, the direct 
method of heating in Fig. 29 and the indirect 
method of Fig. 30 show two forms of apparatus 
for admitting air to buildings that are quite gener- 
ally employed for ventilation of dwellings. In the 
use of all such devices for ventilation purposes, 
there should be provided means of escape of air 
corresponding in amount to the fresh air admitted. 
The exhaust air vent should be located near the 
floor to bring about the best results. The degree 
of success attending the use of such apparatus 
will depend on the amount of care taken, to suit Fig. 16 5.— 
the position of the dampers to the prevailing tester; aiffnstru^ 
weather. 



uU 



ii=^ 



ment used to de- 
termine the qual- 
ity of air. 



The Wolpert Air Tester. — The purity of air is 
expressed by quantity of carbonic acid gas in- 
cluded in its composition. In order to determine the degree of 
purity of any atmosphere the amount of contained gas must be de- 
termined. This is accomplished by use of simple apparatus that 
may be successfully operated by those who are unacquainted 
with chemical analytical methods. The process is due to 
chemical action but the manipulation of the required appa- 
ratus is purely mechanical. 

Fig. 165 shows the Wolpert air tester which is a form of this 



234 



MECHANICS OF THE HOUSEHOLD 



apparatus that has given general satisfaction. The results 
attained by its use are approximate but sufficiently exact for 
all practical purposes. The apparatus consists of a graduated 
glass tube in which fits a rubber piston mounted on a hollow 
glass rod, through which the sample of air is admitted to the tube. 
The chemicals used for absorbing the carbonic acid gas are fur- 
nished with the instrument but may be replenished without 
difficulty. Directions for its use are furnished with the tester 
that may be readily followed after a trial. The results ob- 
tained are read directly from the side of the tube. The tester may 
be obtained from any dealer in chemical or physical apparatus. 
Pneumatic Temperature Regulation. — Pneumatic temperature 
regulation is very generally used in large and complicated heating 



m 
1 




Fig. 166. — Thermostat regulator and motor-valve attached to a radiator. 



systems, because of its positive action and completeness of heat 
control. This method of heat regulation utilizes the energy of 
compressed air, with which to open and close the valves of the 
radiators. It may be adapted to any mode of heating and can 
be used with any size of plant, but is particularly suited to ex- 
tended systems. The radiators, providing heat for any par- 
ticular space, are under control of separate thermostats, 
which by means of motor valves admit heat only as required. 
A motor, operated by compressed air, is attached directly to 



VENTILATION 



235 



[»t^^Y^ 



each radiator valve. Any change in temperature of the room 
causes the thermostat to correct in the radiator the required 
amount of heat. 

With this method of regulation the temperature-controlling 
element of the thermostat, like that of the electro-thermostatic 
system, is a sensitive part, which by expanding and contracting 
with the heat and cold directly controls the heat in any part of 
the building. The motive power for opening and closing the 
valves of steam or hot-water radiators or for operating the dampers 
in a hot-air system is supplied by compressed air. The air supply 
is furnished by an air compressor which auto- 
matically stores air under pressure in a pressure 
tank, from which is drawn the necessary energy, 
as occasion demands. The air is conducted to 
the motors through small pipes which are con- 
nected with the regulating elements and also with 
the motors. The function of the thermostat is to 
so govern the air which enters the motor as to 
correct any change in the temperature of the 
rooms. This it does by opening and closing the 
valves as occasion demands. 

In Fig. 166 is shown the arrangement of the 
thermostat T as it appears on the wall. Air 
from the supply tank is conveyed by the pipe A 
through the thermostat T to the motor valve V at- 
tached to the radiator. The function of the 
thermostat is that of so controlling the radiator 
valve by means of the motor V that the radiator will give out 
just sufficient heat to keep the room at the desired temperature. 
A closer view of the thermostat is given in Fig. 167. 

The thermostat illustrated in Fig. 167 is that employed by 
the National Regulator Co. The drawing shows the exterior 
and interior construction of the parts enclosed in the previous 
illustration. The pipe C at the right and opening P at the 
left are the same as A in Fig. 169; likewise, the pipe D connects 
at the opening M of the motor valve in Fig. 169. 

Referring again to Fig. 168, the sensitive part consists of a 
tube A of vulcanized rubber. It is the dark-shaded part in the 
left-hand drawing. Any change in the air temperature influ- 



FiG. 167.— 
Outside view of 
thermostat as it 
appears in use. 



236 



MECHANICS OF THE HOUSEHOLD 



ences the length of this tube. The changing length of the tube 
effects the air supply to close the radiator valve when the tem- 
perature rises above the desired amount and to reopen it when 
more heat is required. A finely threaded screw passes through 
the plug H at the top and to this is secured the indicating disc 
X. The bottom of this screw is cupped to receive the point of 
the rod K, which connects with the piece L. Any change in 
length of the sensitive tube moves the valve lever 0, and thus 
opens or closes the air port G. 

Air under pressure is supplied by the pipe C, connected to 
the air supply, flowing into the thermostat through the filter 

P, the restriction S, the passage T, and 
the port G. The adjustment of the 
thermostat for different temperatures 
is provided for by the screw J through 
the top plug H, and the indicating disc 
X. The screw R in the connector Q at 
the base of the thermostat is a needle 
valve which opens or closes the connec- 
tion with the air supply, and is used as 
an air shut-off valve when it is desired 
to remove the thermostat. The screw 
aS is a restriction valve which controls 
the supply of air to the thermostat, 
and this screw is set so as to allow the 
air to pass in a restricted quantity. 

When the temperature of the apart- 
ment has risen so as to expand the 
thermostatic element A, the pressure on 
K and L is relieved and the spring N 
closes the port G. The air admitted through the restriction 
screw S, since it cannot escape through the port G, accumu- 
lates in the passage Y and pipe 2), filling the diaphragm and 
moving the valve into the position to decrease the supply of 
heat. When the temperature of the apartment has decreased 
so as to produce pressure on the connecting rod if, through 
the contraction of the thermostatic element A, the port G will 
be opened by the valve lever 0, allowing the air in the pipe D, 
together with that which flows through the restriction /S, to 




Fig. 168. — Internal con- 
struction of the National 
Regulator Co.'s thermo- 
static regulator. 



VENTILATION 



237 



escape through the passage W to the atmosphere, allowing no 
air to accumulate in the pipe D, and thus permitting the spring 
at the diaphragm to actuate the damper or valve for more heat. 
The amount of air released through the port G by the valve 
lever varies the pressure accumulated in the pipe D and pro- 
duces the graduated or intermediate action desired. 

A further application of air pressure in temperature regulation 
is that of the type of motor shown in Fig. 170. This device is 
intended to open and close dampers such as are used in the auto- 
matic regulation of temperature where heated air is used to warm 
the buildings. The operation of the motor is the same as that 
which controls the steam valve. The pressure exerted by the 
diaphragm is applied at A and the attachment to the damper is 



M^ 


r^ 






W^ 


^5^ 






y ^^ 








\l\ 








^ / 


I 








D i 
a 


^ 


l. 


^ 








i 




i^ 






Fig. 169. — Cross-section of Fig. 170. — Pneumatic motor valve for 
pneumatic radiator valve show- automatic control of dampers, etc. 
ing its internal construction. 

made at B. The motors indicated at V and N in Fig. 174 and 
D in Fig. 175 are examples of its application. 

Mechanical Ventilation. — Draft ventilation produced by open 
windows, flues and chimneys is influenced by extremes of tem- 
perature and by the force and changing direction of the wind; 
it is, therefore, but imperfectly controlled. The superiority of 
mechanical ventilation is generally recognized because the 
amount of entering air may be regulated to suit any circum- 
stance and its temperature and humidity varied to conform to 
any desired atmospheric conditions. Mechanical yentilating 
plants arc seldom employed in any but the more pretentious 
dwellings, but their use has extended to a degree that they are 
occasionally installed in apartment buildings and their further 



238 



MECHANICS OF THE HOUSEHOLD 



application is likely to grow. Neither the cost of installation 
nor the expense of operation is prohibitive in dwellings of the 
better types. Mechanical ventilation is quite generally employed 
in school buildings, auditoriums, hospitals, public buildings and 
others where means will permit, and there is a universal recogni- 
tion of the effects of the agreeably conditioned air. 

Mechanical ventilation may be accomplished by power-driven 
fans, either by exhausting the air from the building or by forcing 
air into it, and under some conditions a combination of the two 
methods is used. 




Fig. 171. — Exhaust fan for Fig. 172. — Ventilation apparatus in which is 
induced ventilation. included the heater coils, the fan and the motor. 



The exhaust method of ventilation is that in which air is blown 
out of the building by a fan; and the supply, to replenish that 
taken away, is conducted into the building through ducts pre- 
pared for the purpose. In some cases the induced air supply 
leaks into the rooms through the joints in the doors and windows, 
and through the accidental crevices. In Fig. 171 is shown a 
simple exhaust fan installed to produce such a change of air. 
It is suitable for kitchens and other places where it is desired to 
eliminate smoke or gases rather than to produce a supply of air. 
With this apparatus the air of the room is blown out by the rotat- 
ing fan and new air to take the place of that exhausted is drawn 
in at any convenient opening. 



VENTILATION 239 

The Plenum Method. — That form of mechanical ventilation 
by means of which air is forced into the rooms is known as the 
plenum method. It is the most positive means of air supply 
because its action is attended by a slight pressure above the 
outside air; it is continuous in action and the amount of enter- 
ing air is under control. The escape of the expelled air is made 
through vent flues especially constructed for the purpose. 

Ventilation Apparatus. — Fig. 172 illustrates the form of appara- 
tus used for ventilating buildings where no attempt is made at 
washing or humidifying the air. Enclosed in a sheet-iron case 
C is a fan which is driven by the electric motor ilf . The capacity 
of the fan, for the delivery of air, is made to suit the require- 
ments of the building. In this case the fan is secured to an 
extension of the armature shaft of the motor. Connecting with 
the case which encloses the fan is another sheet-iron box H, 
containg coils of heating pipe. The heating apparatus is designed 
to change the temperature of the entering air to suit the require- 
ments of the building. 

This represents the draw-through or induced-draft type of 
ventilation apparatus. The air delivered by the fan induces a 
flow of outside air which is drawn through the heating coils and 
discharged through the opening E, At this point it enters the 
main ventilation duct from which it is distributed by branch 
conduits throughout the building. 

The temperature of the air sent out from the fan is regulated 
by the steam valves of the heater coils to suit the prevailing 
conditions. Under some installations of this character the venti- 
lating air is made to furnish the heat necessary to warm the 
building as well as to provide its air supply. As ordinarily 
used, however, the temperature of the ventilating air is the 
same as that of the room. 

The method of conveying air to the various apartments 
depends entirely on local conditions. The conduits may be 
made of sheet iron, placed to suit the existing conditions; but 
when a building is constructed with a ventilating plant in view 
as a part of the building equipment, it is customary to make the 
ducts part of the partitions. In brick buildings the ducts are 
constructed, so far as it is practicable, in the walls. These 
ducts are made in size and arrangement to suit the amount of 



240 MECHANICS OF THE HOUSEHOLD 

air required for each room. When the plant is put into operation 
each duct is tested with an anemometer which indicates the 
velocity of the entering air. The calculated amount of air, deter- 
mined by the velocity and area of the entering column, when 
compared with the necessary quantity demanded for good 
ventilation, gives the efficiency of the system. 

Air Conditioning. — In addition to the possibility of a constant 
supply of air, a combination of the exhaust and plenum methods 
admits of air purification. With such a plant, the air may be 
washed free from all suspended dust or gases and moistened to 
any degree of humidity. The process of washing and humidi- 
fying air is known as air conditioning. Apparatus for air condi- 
tioning is made in a variety of forms to produce any desired 
extent of air purification and any degree of humidity. The 
plant may be regulated by hand or it may be made entirely 
automatic in its action. Air-conditioning plants may be arranged 
to produce air that is purified, humidified and warmed during 
winter weather and in suinmer the hot humid atmosphere may be 
cooled and dehumidified to a temperature and percentage of 
moisture that is most agreeable. 

Conditioned air is often used in manufactories, not for the 
purpose of supplying good air to the employees but because of 
the effect of the atmospheric air on the products. The manufac- 
ture of textile fabrics often demands a constant atmospheric 
humidity in order that the material produced may be uniform 
in grade; this is particularly true in the making of silks. Vari- 
ous manufactories require an atmosphere free from lint and 
dust in order that the best quality of material may be produced. 
The air for ventilation in such places is washed free from all 
suspended matter before being sent into the building. 

In Fig. 173 is indicated an application of apparatus similar 
in construction to that just described. The arrangement of 
the parts is such as to produce a Plenum hot-air system of venti- 
lation and temperature regulation. 

The plant occupies a room in the basement and the drawing 
shows the method of heating, together with the plan of distribu- 
tion. The air duct leading to the room above furnishes an 
example of the manner of admitting the warmed air to the rooms. 
The dampers Ci, (72, etc., are controlled by separate motors. 



VENTILATION 



241 



The motor M is under the control of the thermostat T in the 
room above. Any change of temperature in the room is cor- 
rected by the damper to admit cold or warm air as is desired. 

The power-driven fan F draws in outdoor air from an opening 
A J through a set of heater coils Hi, in which it is raised consider- 
ably in temperature. The heater in this case is a coil of steam 
pipes. The air — after being warmed — is taken into the fan and 
from it may be sent through a second set of coils H^, to receive 
additional heat, or if already sufficiently warmed the air from 
the fan may pass under the second set of coils and receive no 
heat from them. Under the first heater coil is also a bypass 




Fig. 173. — Plenum hot-blast heating system with temperature regulation. 



which may be opened by the motor N to admit cold air that is 
drawn directly into the fan. The movement of the air through 
these bypasses is under control of the thermostat, which causes 
the motor N to open or close the bypass to suit the temperature 
of the room. When the bypass is opened the steam is shut 
off from the heater coils. 

Examination of the drawing will show that the air from the 
fan may pass through a second heater 7^2, to the place marked 
warm air, or it may pass under the heater to the compartment 
marked cold air. The amount of warm and cold air which enters 
the duct is regulated by the position of the dampers C. 

16 



242 MECHANICS OF THE HOUSEHOLD 

The position of the dampers C, which is controlled by the 
motors M, is made to take amounts of cold or warm air to pro- 
duce the desired temperature in the rooms. The motors Ci, 
etc., are under control of the thermostat in each room. Any 
change of temperature in the room will immediately affect the 
thermostat. The effect on the thermostat will so change the 
air pressure in the motor that the valve C is moved to correct 
the difference in room temperature. If warm air is demanded, 
the motor changes the damper C to close the cold-air supply and 
take air that must pass through the heater coils H^. If only 
cold air is desired the damper will turn to shut off the course 
through the heaters and admit air directly from outdoors. 

Humidifying Plants. — Mechanical ventilation plants that are 
intended for washing the air may be made up of parts similar to 
that of Fig. 173, but in addition to the apparatus shown provision 
is made for the air to pass through a chamber filled with a spray 
of water. The air in passing through this spray is washed free 
of dust and at the same time absorbs water necessary for its 
desired humidity. 

The humidity of air may be increased by the addition of mois- 
ture or decreased (dehumidified) by raising its temperature, there- 
by increasing its capacity for containing moisture. Suppose that 
air at 50° is saturated with moisture; it will contain practically 
4 grains of water per cubic foot. If now the temperature of the 
air is raised to 70°, the same amount of air is capable of contain- 
ing 8 grains of water and is, therefore, only 50 per cent, saturated. 

Humidification is accomplished in air-conditioning plants 
through one of two general methods : by the evaporation type of 
apparatus, in which the passing air absorbs moisture from con- 
tact with a large area of water; or the spray method, in which 
the water is broken into a very fine spray by a specially devised 
nozzle and thus rendered easy of absorption by the air to be 
moistened. A third method is sometimes employed, in which 
steam is introduced into the air supply. Steam is already vapor- 
ized water and immediately becomes a part of the air without 
further change. The steam type of humidifying plant possesses 
features that hmit its appHcation, in that the steam in some cases 
may possess objectionable odor or includes the vapor of grease, 
either of which would materially effect its use. Further, the 



VENTILATION 243 

heat of vaporization liberated by the condensing steam is also 
a factor that influences the temperature of the air and in case 
of direct humidification must receive special attention. 

Vaporization as a Cooling Agent. — The evaporation of water 
has a distinct value aside from humidifying the air, in that 
the cooling effect is in direct proportion to the added moisture. 
In the process of evaporation the heat necessary to change the 
water into vapor is taken from the surrounding air and the tem- 
perature is thus materially lowered. 

In practical air-conditioning apparatus, of the evaporative or 
spray types, the process consists of drawing the outside air into 
a chamber filled with falling water that is broken up into drops 
like rain or spray. In passing, every particle of the air comes into 
contact with the water drops; the almost invisible particles of 
dust adhere to the water and are carried away leaving the air 
washed clean. In addition to freeing the air from dust, the 
intimate mixture of the air permits of a ready absorption of the 
water, which is taken up to any per cent, of saturation. After 
leaving the spray chamber, the moisture-laden air passes through 
an eliminator in which any unabsorbed moisture is extracted. 
It is possible for air to become not only completely saturated 
with water under the conditions encountered in a humidifying 
plant, but in addition, the movement of the air may carry along 
unabsorbed particles that are precipitated directly after leaving 
the spray chamber. For this reason the air is passed through an 
eliminator. 

The eliminator is composed of a series of irregular sheet-met a 
surfaces so arranged that the air is required to abruptly change 
its direction several times in its passage of a short distance. The 
impact of the air against the surfaces and the centrifugal force 
exerted by the sudden changes of direction throw out the excess 
moisture and any remaining suspended matter the air may contain. 

The saturated air from the eliminator passes through a heater 
where the temperature is raised to that of the rooms. In the 
rise of temperature the air which is saturated is rendered capable 
of absorbing more moisture, and hence has been dehumidified. 
The rise of temperature and the corresponding decrease in relative 
humidity is intended to be such as to leave in the finished air 
the desired percentage of moisture. 



244 MECHANICS OF THE HOUSEHOLD 

Air-cooling Plants. — The use of air-washing and humidifying 
plants so far mentioned has been confined to elimination of 
dust and the addition of moisture to air, under winter conditions. 
The same type of apparatus, used in summer, becomes a cooling 
plant, and by observance of the necessary requirements may be 
used to produce agreeable atmospheric conditions during hot 
weather. 

When used for such purpose the air is washed, by passing it 
through falling water which frees it from dust and reduces its 
temperature. It is then further cooled by passing over cold 
surfaces that take the place of the heaters used in cold weather. 
The cooling surfaces are pipe coils kept cold by the contained 
water which comes from the water supply or from a refrigerating 
plant. The temperature and humidity are thus changed to suit 
the requirements of the conditioned air. 

During the hot weather of summer the most disagreeable 
atmospheric condition is that caused by humidity near saturation, 
at a time of relatively high temperature. Under such conditions 
the cooling plant not only cools the air, but causes a precipitation 
of the moisture on the cold surfaces which are kept below the 
dew-point. The air is cooled and dehumidified to a point such 
that the conditioned air produces an agreeable atmosphere. 
The regulation of the degree to which the air is cooled is accom- 
plished by the same general methods as are used in heating. 

Humidity Control. — The method of regulating atmospheric 
humidity in a humidifying plant will be determined by the con- 
ditions under which it is intended to work. There are a variety 
of means employed that may be used to bring about the same 
effects, each of which is particularly suited to certain require- 
ments. The present object is to describe the essential features of 
airconditioning plants, by use of illustrations representing each 
of the three methods mentioned above. That of the ventilation 
of a school building under winter conditions will be taken as 
an example. 

In Fig. 174 is shown a heating and ventilating system in which 
the air conditioning is accomplished by automatic regulators 
for both temperature and humidity. The plant occupies a room 
in the basement, and a room directly above illustrates the condi- 
tions that prevail in all of the other rooms of the building. The 



VENTILATION 



245 



principal features of the plant are the fan G, which supplies the 
air; the hot-air furnace H, which furnishes the heat; and the 
water spray S, which provides the moisture with which the air 
is humidified. 

The air is drawn in at A to a room in which a motor-driven 
fan G forces the supply through the heating apparatus into the 
building. The air after leaving the fan passes through a cold- 
air duct C to the 'heating surfaces H to be warmed. The air 
in passing over the heating surfaces is raised to a degree consider- 
ably above the temperature of the rooms. The hot air leaving 
the heater H enters the tempered air chamber T through the pas- 
sage K. A damper M provides means for also admitting cold 




Fig. 174. — Furnace blast system of heating, with temperature reguhition and 

humidity control. 

air to the chamber T directly from the fan. The thermostat, 
located at 0, is connected with a. pneumatic motor V (similar to 
Fig. 170) which regulates the supply of cold and hot air from K 
and M to suit the desired temperature of the air supply for the 
rooms above. The arm of the motor V is so arranged that an 
upward movement opens the cold-air and closes the hot-air 
passages; the downward movement produces the opposite effect. 
The motor V thus controls the temperature of the air. 

In this system the air is humidified by a direct water spray 



246 



MECHANICS OF THE HOUSEHOLD 



marked S in the drawing. A part of the hot air from the heater 
H may escape through the damper W and absorb water on its 
way to the duct D, which takes the air to the room above, where 
it enters through the register E, This air as it comes from the 
heater, being hot, will absorb a larger amount of water than the 
air could hold when cooled to room temperature; for this reason 
only a part of the air supply is humidified. The supply of the 
hot humid air is admitted to the duct D in siich quantity as will 
produce the desired degree of humidity in the rooms. 

The degree of room temperature is governed by the thermo- 
stat, in the room, which, by means of the motor iV, controls the 




Fig. 175. — Direct steam heating system with mechanical fan-blast ventilation, 
temperature regulation and humidity control. 



damper F, This damper admits hot humid air and the tempered 
air from the chamber T in proper proportion. At any time the 
humidity of the air in the room reaches the maximum amount for 
which it is set, the humidostat, through its motor, closes the valve 
Rj which controls the water supply to the spray nozzle, and the 
moisture in the air is reduced until a further amount is demanded. 
With apparatus of this kind the temperature and humidity may 
be kept practically constant. 

Fig. 175 shows another arrangement of a similarly controlled 
plant in which steam is used for humidifying the air. The air is 



VENTILATION 247 

admitted at A, from whence it passes through a steam-heating 
coil >S, which raises it to a predetermined temperature. The 
steam jets are arranged at H^ for providing the necessary mois- 
ture. The humidostat through a motor valve V governs the 
amount of steam that is permitted to enter the humidifying 
chamber. A thermostat located in the air duct at B controls the 
temperature of the air sent to the rooms by regulating the amount 
of heat given out by the steam coils S, This control is made 
still more sensitive by use of a cold-air bypass. The damper D 
is opened by a motor valve to admit cold air at the same time 
the steam is shut off from the heater coils. 

In this plant the ventilating air is not intended to supply all 
of the heat to the rooms. A thermostat on the wall controls the 
room temperature by regulating the amount of steam admitted 
to the radiators. In the ventilating plant previously described, 
all of the heat for the building is supplied through the ventilating 
system; in the plant shown in Fig. 175, the heating apparatus 
which warms the building is entirely separate and may be used 
when the ventilating system is inoperative. 

The humidity is controlled by admitting saturated air to the 
warmer air of the rooms in such quantity as will produce the 
desired mixture. The humidostat, on the left-hand wall, regu- 
lates the quantity of moisture by opening or closing the steam 
valve V as occasion requires. 

Another example of air-conditioning plant similar in principle 
to that just described is often called the dew-point system. It 
depends for its action on a definite dew-point temperature at 
which the air is saturated with moisture, before being heated to 
room temperature. The air to be conditioned is first warmed, by 
passing through a set of tempering coils, to a degree at which it 
will contain the necessary moisture when saturated. After 
saturation the temperature is raised by a second set of heating 
coils to the room temperature, the moisture contained being right 
to give the desired humidity. 

To illustrate, suppose that it is desired to maintain a constant 
humidity of 50 per cent, saturation at 70°F. in the building. The 
temperature at which the air nmst be saturated, to contain 4 
grains of moisture per cubic foot, is found in the table on page 199 
to be 48°F. 



248 



MECHANICS OF THE HOUSEHOLD 



The entering air must first be raised to that temperature by 
the tempering coils. The air then enters the spray chamber 
where it absorbs moisture to saturation, by contact with a 
multitude of water particles. This saturated air now passes 
through a second set of heated coils and takes up heat sufficient 
to raise it to the finished temperature. 

The dew-point temperature at which the air enters the spray 
chamber and the final temperature are kept constant by motor- 
operated valves which supply the heating coils with the necessary 
heat in the form of steam. The motors are controlled by 
thermostats, placed to measure the temperature of the air as it 




'),ffl!flillll!!iiiii.':;!J 

Fig. 176. — School building section showing a complete air-conditioning plant. 

enters the saturator and the finished air as it enters the rooms. 
If these conditions are now kept constant, the finished air will 
be constantly 50 per cent, saturated. 

A plant of this character is illustrated in Fig. 176. The figure 
shows the exterior of the casings which enclose the tempering 
coils and saturator at A, the eliminator at B, and the heating 
coils at C This is another draw-through type of plant where a 
fan, enclosed in D, draws the air through the conditioning 
apparatus and forces it through the sheet-iron ducts E, The 
passages in the walls — as indicated by the arrows — conduct 
the air through the register R, into the room. The register S 



VENTILATION 249 

represents the discharge duct through which the vitiated air 
is forced from the room. 

In this system of air conditioning, all of the ventilating air is 
to be saturated with moisture at a temperature such that when 
raised to room temperature will contain the desired percentage 
of humidity. The saturator occupies the space between A and B, 
A number of spray jets are arranged to fill the entire space with 
water drops that are moving in every direction. The air, as it 
passes, must come into contact with the drops again and again, 
until by repeated impact each particle is completely saturated 
and at the same time washed free from dust. It has already been 
explained that the movement of the saturated air through a mass 
of spray will carry with it a considerable amount of unabsorbed 
water that must be taken out by an eliminator. A section of the 
casing is broken out at 5, showing the eliminator plates. The 
irregular surfaces of these plates repeatedly change the direction 
of the passing air, and the suspended water or remaining solid 
matter is thrown against the surfaces where they adhere. The 
moisture accumulates in drops of water that run down the plates 
to the bottom of the enclosure and finally into the sewer. 

From the eliminator the air passes through the heating coils 
enclosed in C, where it is heated to the necessary temperature for 
admission to the rooms. 

The regulation of the temperature of the tempering coils and 
heating coils is accomplished as in the other plants described. 
The thermostats with their motors operate the valves of the 
heaters to admit steam sufficient to keep constant temperatures 
at the different parts. The humidity is maintained at a con- 
stant amount by saturating the air at a constant temperature and 
therefore no humidostat is required. 



CHAPTER XII 
GASEOUS AND LIQUID FUELS 

Gaseous and Liquid Fuels.— Gaseous and liquid fuels used for 
domestic illumination and heating may be divided into three 
general classes — coal gas, including carburetted water gas and 
producer gas and their various mixtures; oil gas, acetylene and 
gasoline gas. Of these the first is the most important as an 
illuminating gas, while for industrial and domestic purposes 
producer gas is of no importance as a fuel gas. Gasoline, acety- 
lene and oil gases are generated and used to a remarkable extent 
in isolated dwellings as fuel and for illumination. 

The value of any gas for domestic purposes will depend on the 
amount of heat that is produced when it is burned. In the earlier 
days of its use coal gas was employed entirely as an illuminant 
and its value was expressed in illuminating power; at the present 
time the standard often prescribed by regulation is that of its 
illuminating capability and is stated in candlepower. There 
is, however, a tendency to establish the more consistent standard 
of expressing the value of gas by its heat value. The reasons for 
this is the general use of mantle gas burners which depend on the 
heating value alone for their efficiency and the fact that coal gas is 
very extensively used for domestic fuel. 

Coal Gas. — Coal gas is derived from the solid hydrocarbons of 
coal transformed into the more convenient, gaseous form of fuel 
by means of distillation. Coal gas was first made by distilling 
coal from an iron pot over a fire and to some extent this is still 
the principle of the present practice. The gas as it comes 
from the retort is subjected to a refining process of washing and 
scrubbing to remove the undesirable properties when it is stored 
in a large gasometer for distribution through pipes to its places 
of use. Coal gas is now used largely for fuel as well as for light- 
ing. Unless the heating value of gas is regulated by law in any 
community and determinations of its quality are made regularly 

250 



GASEOUS AND LIQUID FUELS 251 

by some competent official, the amount of heat contained in coal 
gas is entirely at the option of the manufacturer and manager's 
conscience. The value as given in the table on page 252 is the 
number of B.t.u. coal gas should contain. The heating value of 
any gas is determined by burning the gas in a calorimeter made 
expressly for the measurement of the heat of combustion for 
each foot of the gas consumed. 

All-oil Water Gas. — In places where an abundant supply of 
cheap oil is available, all-oil water gas has met with a great deal 
of favor. It is made by atomizing crude oil by a blast of steam 
in a heated chamber where a combination of the vaporized oil 
and steam form a gas. In general the gas resembles coal gas 
and as given in the table on page 252 is slightly higher in heating 
value. 

Pintsch Gas. — One of the commercial adaptations of oil gas is 
that of the Pintsch process of compressing the gas in tanks for 
transportation. In the Pintsch process, the gas is subjected to 
a pressure of 10 atmospheres — about 150 pounds. This con- 
densation permits a sufficiently large volume of gas to be stored 
in tanks as to make possible the lighting of railroad trains, etc., 
by gaslight. The pressure of the gas is reduced by an automatic 
regulating valve to that required by the burner. The flame is 
very much the same as that produced by coal gas. 

Blau Gas. — Another commercial adaptation of oil gas is that 
known as Blau gas. In this process of storage the gas is sub- 
jected to 100 atmospheres of pressure — about 1500 pounds. This 
pressure is sufficient to liquefy the gas and as a result a large 
amount can be transported in a relatively small space. Accord- 
ing to Fulweiler 1 gallon of the liquefied gas will yield about 28 
cubic feet of the expanded gas and there will remain a residue 
that may run up to 9 per cent. 

Water Gas. — When the vapor of water is brought into con- 
tact with incandescent carbon, the water is decomposed and 
sufficient carbon is absorbed to produce a fuel gas. Its manu- 
facture depends on the decomposition that takes place when 
steam is blown into a bed of incandescent coal. The gas made 
by this reaction is a water gas, but due to the fact that when 
burned it gives a blue flame, it is known as ^^blue gas.'' It has 
a heating value of about 300 B.t.u. per cubic foot, and as com- 



252 MECHANICS OF THE HOUSEHOLD 

pared with coal gas which gives 622 B.t.u. per cubic foot, would be 
reckoned at about one-half its value as a heating agent. Blue 
gas may be rendered luminous by the addition of some hydro- 
carbon that will liberate free carbon in the flame when burned. 
This is accomplished in the process of manufacture by the addi- 
tion of vaporized oil. 

The following table as stated by Fulweiler gives the heating 
values of the gases commonly used for domestic purposes in 
British thermal units per cubic foot. 

Coal gas 622 B.t.u. 

Carburetted water gas 643 B.t.u. 

Pintsch gas 1,276 B.t.u. 

Blau gas 1,704 B.t.u. 

All-oil water gas 680 B.t.u. 

Acetylene gas 1,350 B.t.u. 

Gasoline gas 514 B.t.u. 

Oil gas 1,320 B.t.u. 

Blue water gas 300 B.t.u. 

The cost and calorific values as computed by Dr. Willard of 
the State Agricultural College of Kansas, given below, shows the 
relative values of various kinds of domestic fuels. 

Cost per Cal. per Cal. for 
pound Gram 1 cent 

cents 

Wood, 20 per cent. H.O. $ 5 . 00 per cord . 167 2.3 7,620 

Bitu. coal $4.25 per ton 0.213 7.5 16,009 

Ant. coal $12 . 50 per ton . 625 6.0 4,354 

Gasoline, sp. gr. 68 $ 0.14 per gallon, 5% 

pounds... 2.470 10.0 1,846 

Kerosene, sp. gr. 80 $ 0.11 per gallon 6% 

pounds 1 . 650 10 . 2,753 

Coal gas, 1.50 per 1000 cubic feet 3 . 100 20 . 2,927 

Alcohol, 90 per cent., 50 per gallon, 7 pounds. . 7.140 6.4 404 

Electricity, 0.15 per kilowatt-hour 57 . 4 

The relatively high heat value of Blau gas (1704 B.t.u.) and the 
fact that it may be reduced to a liquid form for transportation 
has resulted in the manufacture of small lighting plants that may 
be used in places where other forms of liquid or gaseous fuel are 
not desirable. 

For transportation the gas is compressed in seamless, steel 
bottles that contain about 20 pounds of liquid. The charged 



GASEOUS AND LIQUID FUELS 253 

bottles are shipped to the consumer and when empty are returned 
to the manufacturers to be refilled. 

The entire plant — ready to be attached to the distributing 
pipes in the house — is contained in a steel cabinet. The charged 
tanks are attached to a larger tank into which the liquid gas is 
first expanded. This expansion is accomplished by an automatic 
valve that maintains a constant pressure in the large tank. 
With this plant the lamps and burners of the stoves are operated 
as with city gas — no generating or preliminary preparation 
being necessary. As soon as the bottles are exhausted they are 
replaced by others and the empty bottles are shipped to the fac- 
tory to be refilled. 

Measurem.ent of Gas. — When gas of any kind is purchased 
from a manufacturing company, the amount used is measured by 
a gas meter, located at the point where the gas main enters the 
building. The readings of the meter are taken by the company 
at stated, intervals and the amount registered is charged to the 
account of the consumer. Gas is sold in cubic feet and is so 
registered by the meter. The price is quoted by the manufac- 
turers at a definite rate per thousand cubic feet. The difference 
between the last two readings of the meter furnishes the amount 
from which the gas bill is reckoned. 

The occupants of a building are responsible for all gas registered 
by the meter and, therefore, should be acquainted with the 
conditions under which the gas is sold. Gas bills are often the 
subject of dispute because of failure to understand the period of 
time covered by the amount claimed; again, the varying length 
of days due to the season of the year has a pronounced effect 
on the amount of gas consumed. Lack of care in the economical 
use of gas is probably the most prolific cause of disputed bills. 

The amount due for gas may at any time be checked by the 
consumer who keeps a record of the meter readings. At any 
time the correctness of a meter is doubted, arrangement may be 
made with the gas company to have it tested for accuracy. 
This is done in the office of the company, by attaching the meter 
to a measuring device — called a meter prover — in which a definite 
measured amount of gas is passed through the meter and com- 
parison m,ade with meter registration. If it is found that the 
meter does not register correctly, the gas company is in duty bound 



254 



MECHANICS OF THE HOUSEHOLD 



to make good the difference. If, however, the meter is found to be 
correct, it is customary to charge for the services of proving the 
meter. 

Gas Meters. — The gas meter as ordinarily used is shown in 
Fig. 177. In Fig. 178 the same meter is shown with the top and 
front exposed. 

The meter is operated by the pressure of the gas which enters 
at the inlet pipe on the left-hand side of the meter as you face 
the index. The gas from this pipe comes into the valve chamber 
and passes alternately into the diaphragms and their chambers, 
as the valve ports V are opened and closed by the action of the 





Fig. 177. — Gas meter. 



Fig. 178. — Gas meter show- 
ing internal mechanism. 



meter. The movement of the valve in opening the port which 
admits gas to the diaphragm closes the port to the chamber 
which has filled. The gas entering the diaphragm expands it 
like a bellows and forces the gas out of the chamber, through 
the middle part of the valve into the outlet pipe F, While this 
action is going on, the gas is entering the case compartment on 
the opposite side of the meter and also forcing the gas from its 
diaphragm through the opening F. 

While the meter is in operation, one of the diaphragms and 
one of the case compartments are filling while the others are 
emptying. The movement of the diaphragm discs is transformed 
to the recording dial by the connecting levers shown at the top 



GASEOUS AND LIQUID FUELS 255 

of the figure. The movement of these levers is such as to pro- 
duce a rotary motion to a tangent which is attached to a shaft 
that operates the recording dial. The tangent is carried around 
in a circle by the action of the arms and its movement is regis- 
tered on the index of each cycle of the diaphragms. 

The measurement is accomplished by the displacement of a 
definite amount of gas with each movement of the discs; first, 
from the chamber and then from the diaphragms. 

HOW TO READ THE INDEX 

The index of a gas meter looks quite complicated, but it is 
really a very simple contrivance. The small circle on the top 
in Fig. 177 is for testing purposes only and need not be considered. 
The dial of Fig. 177 is shown in Fig. 177-4. The first circle, 
marked 1 thousand, registers 100 feet for each figure, 1000 feet 
for the entire circle. If the pointer stood on 9 it would mean 
900 cubic feet. The second circle registers 1000 for each figure, 
or 10,000 for the entire circle. When the pointer of the first 
circle has been around once, it reaches on that circle, but 
the hand on the second has moved to figure 1, showing 1000 
feet used. The process goes on until the pointer of the second 
circle has traveled around and stands at zero. The pointer on 
the third circle, however, has moved to 1, indicating 10,000. 
This explanation shows the general plan of the index. A few 
minutes study of it will render the index as easy to read as the 
face of a clock. Of course, the pointers do not always stand 
exactly on the figures as they move from figure to figure as the 
gas is used. 

Suppose your index stood like this: 




Fig. 177^. — Gas-meter dial. It reads 38600 cubic feet. 

Take the figure 3 on the 100 thousand circle, the figure 8 on 
the 10 thousand, and the figure 6 on the 1 thousand, and you have 



256 



MECHANICS OF THE HOUSEHOLD 



30,000, 8000, and 600, or 38,600 feet. To ascertain the quantity 
of gas used in the time elapsing between the readings of the meter, 
subtract the quantity registered at the previous reading. Thus, 
if the previous reading was 38,600 feet, and the next reading 
40,100 feet, the pointers standing thus: 




Fig. \77B. — Gas-meter dial. It reads 40100 cubic feet. 

You have 40,100 

Subtract your last reading 38,600 and you find 



that your bill should be for 1,500 feet 

When 100,000 feet have been passed, the index is at zero; that 
is, all the pointers stand at 0, and the registration begins all over 
again. 

Prepayment Meters. — In many places it is desirable to sell 
gas in small quantities and to prepay the amount for a given 

supply of gas. This is accomplished by 
a meter such as that of Fig. 179. The 
meter is constructed much the same as the 
former but provided with a mechanism 
such that when a coin — usually 25 cents — 
is deposited, according to the printed 
directions in the instrument, an amount 
of gas representing the proportional cur- 
rent rate is allowed to pass the meter. 
The supply is cut off as soon as the 
amount paid for is used; when in order 
to receive more gas, another coin must be 
deposited as before. 
Gas-service Rules. — The rules for the regulation of gas serv- 
ice are in many States under the control of a board or commis- 
sion whose duty it is to form codes prescribing the measurement 
and sale of all public utilities. The following form. General 
Order No. 20, State Public Utilities Commission of Illinois, 




Fig. 179. — The prepay- 
ment gas meter. 



GASEOUS AND LIQUID FUELS 257 

gives an idea of the requirements in that State for the sale of 
coal gas. 

Rule 3. Request Tests. — Each utility furnishing metered service shall 
make a test of the accuracy of any meter, upon written request by a con- 
sumer: Provided, first, that the meter in question has not been tested by the 
utility or by the commission within 6 months previous to such request; 
and second, that the consumer will agree to accept the result of the test 
made by the utility as determining the basis for settling the difference 
claimed. No charge shall be made to the consumer for any such test. A 
report, giving the result of every such test, shall be made to the consumer. 

Rule 4. Adjustment of Bills for Meter Error. — If on any test of 
a service meter, either by the utility or by the commission, such meter shall 
be found to have a percentage of error greater than that allowed in Rule 1 1 
(see below) for gas meters, the following provisions for the adjustment of 
bills shall be observed. 

(a) Fast Meters. — If the meter is faster than allowable, the utility shall 
refund to the consumer a percentage of the amount of his bills for the 6 
months previous to the test or for the time the meter was installed, not ex- 
ceeding 6 months, corresponding to the percentage of error of the meter. 
No part of a minimum, service or demand charge need be refunded. 

(h) Slow Meters. — If the meter is found not to register or to run slow, the 
utility may render a bill to the consumer for the estimated consumption 
during the preceding 6 months, not covered by bills previously rendered, but 
such action shall be taken only in cases of substantial importance where the 
utility is not at fault for allowing the incorrect meter to be in service. 

Rule 11. Gas-meter Accuracy. — (a) Method of Testing. — All tests to 
determine the accuracy of registration of a gas service meter shall be made 
with a suitable meter prover. At least two test runs shall be made on each 
meter, the results of which shall agree with each other within one-half 
per cent. {}A%). 

(c) Allowable Error. — Whenever a meter is tested to determine the ac- 
curacy with which it has been registering in service, it may be considered as 
correct if found not more than two per cent. (2%) in error, and no adjust- 
ment of charges shall be entailed unless the error is greater than this amount. 
. Rule 15. Heating Value. — Each utility furnishing manufactured gas 
shall supply gas which at any point at least 1 mile from the plant, and tested 
in the place where it is consumed, shall have a monthly average total heating 
value of not less than 565 B.t.u. per cubic foot, and at no time shall the total 
heating value of the gas at such point be less than 530 B.t.u. per cubic foot. 

To arrive at the monthly average total heating value, the results of all 
tests made on any one day shall be averaged and the average of all such daily 
averages shall be taken as the monthly average. 

Rule 8. Railroad Commission of Wisconsin. — Each utility furnishing 

gas service must supply gas giving a monthly average of not less than 000 

B.t.u. total heating value per cubic foot, as referred to standard conditions 

of temperature and pressure. The minimum heating value shall never 

17 



258 



MECHANICS OF THE HOUSEHOLD 



fall below 550. The tests to determine the heating value of the gas shall be 
made anywhere within a 1-mile radius of the center of distribution. 

Gas Ranges. — Gas ranges and all other heaters using gas as a 
fuel are constructed to utilize the principle of the Bunsen burner. 

Fig. 180 illustrates the type of 
burner used in the Jewel gas 
range. This represents the 
form adapted to the top bur- 
ners for all direct-contact cook- 
ing or heating. The burners 
are of different sizes and ar- 
ranged as they appear in Fig. 
181. This picture shows the 
top of the range as seen from 
above, looking directly down- 
ward. The gas supply pipe 
and individual valves for each 
burner are in position as they 
appear in front of the range. 

In operation, the nozzles of the gas valves stand directly in 
front of the opening G, in Fig. 180. The stream of gas in passing 




Fig. 180. — Detroit Jewel one-piece, 
star-shaped burner. 




Fig. 181. Fig. 182. 

Fig. 181. — Showing top burners and valve attachment of a gas stove. 
Fig. 182. — Section showing arrangement of oven burners and lighter of a gas 
oven. 

into the burner induces a flow of air through the opening A. The 
mixture of gas and air is such as will burn with the characteristic 
Bunsen flame without smoke. 



GASEOUS AND LIQUID FUELS 259 

The oven burners are different in form but the individual 
flames are the same as those of the top burners. They extend 
across the oven as shown in Fig. 182. In this the top of the 
oven is removed and burners as seen are viewed from above. 

The top burners are Hghted by direct appUcation of a burning 
match but the oven burners must be Hghted by first igniting a 
special torch or ^^ pilot lighter.'' The middle gas valve of Fig. 
182 is turned and the torch lighted, then the other valves are 
opened and the jets are instantly ignited. As soon as they are 
burning the pilot lighter is extinguished by turning its valve. 

The reason for this special lighter is because of the possibility 
of explosion at the time of lighting. The gas from the jets is 
mixed with air at the proper proportion to be violently explosive 
and if by chance the gas should be turned on a sufficient time 
to fill the oven with this explosive mixture and then lighted, 
and explosion would be certain, with every possibility of dis- 
astrous consequences. All gas ovens should be lighted in a 
manner similar to that described. 

Lighting and Heating with Gasoline. — The remarkable growth 
of modern cities, the building of small towns in the west, and the 
improvement in suburban and rural homes has created a demand 
for efficient means of illumination in the form of small household 
lighting plants. The development and improvement in electric 
lighting has induced an equal, if not greater, improvement in 
gas lighting. Up to the year 1875, the open-flame 'gas jet 
represented the most improved form of city lighting. Then came 
electricity, which for a time bade fair to supplant all other 
forms of illumination; but the relative high cost of electric light- 
ing, even with the advantages it afforded, was a stimulus to 
improvement in less expensive forms of illuminants. 

The invention of the incandescent-mantle gas burner enor- 
mously increased the opportunities for gas lighting and opened 
an inviting field of endeavor. In a relatively short time, three 
distinct types of gasoline lighting plants for household illumina- 
tion came into common use, with a great number of different 
systems in each type. As a means of economical ilhunination 
the only rival of any consequence to the small gasoline-gas plant 
of today is acetylene. The dangers attending the use of these 
agents of illumination have been rapidly eliminated, until today — 



260 MECHANICS OF THE HOUSEHOLD 

when intelligently managed — they are fully as safe as any other 
means of artificial lighting. Gasoline plants are now in common 
use in cities where competition with all other forms of illumina- 
tion require excellence in service to hold an established place. 

In order that any mechanical appliance may be used with the 
best results, its principle of operation and mechanism must be 
thoroughly understood. In the case of gasoline plants, not only 
familiarity with the mechanism should be acquired but an 
intimate knowledge of gasoline and its characteristic properties 
should be gained, that the peculiarities of the plant may be more 
fully comprehended. 

Gasoline is the first distillate of crude petroleum; that is, in 
the process of separation, the crude petroleum is distilled from 
a retort and the condensed vapors at different degrees of tem- 
perature form the various grades of gasoline, kerosene, lubricating 
oil, paraffin, etc. The crude oil is placed in the still and heated; 
the distillate that first comes from the condenser, at the lowest 
temperature of the still, is gasoline of a light spiritous nature. 
As the process of distillation continues, this part of the petroleum 
is entirely driven off and it is necessary to raise the temperature 
of the still in order to vaporize an additional portion of the oil. 
There is no distinct line of separation between the gasoline that 
first comes from the condenser and that which comes over after 
the temperature is raised, except that it is less of a spiritous 
nature and contains more oily matter. As the temperature of the 
retort is gradually raised, the distillate contains less and less of 
the spiritous and constantly more of the oily matter. 

In order to grade gasoline for the market, the standard adopted 
was that of relative density. The distillations produced at 
various temperatures are mixed to produce various densities 
which form definite grades of gasoline. The Beaume hydrometer 
is a scale of relative specific gravities in which the different 
densities are expressed in degrees. The highest grade of gasoline 
produced by the first distillation is 90°Be.; that is, the hydrome- 
ter will sink in the gasoline to 90° on the scale. As the tem- 
perature of the retort is gradually raised, the distillate becomes 
heavier and the next commercial grade is 86° gasoline. The 
86° gasoline contains a greater proportion of oily matter and a 
less amount of that of a spiritous nature. The next commercial 



GASEOUS AND LIQUID FUELS 261 

grade that is produced, as the temperature is raised, is 76° gaso- 
line, a still highly volatile spirit but containing more oil than 
the last. This process is kept up until there is an amount of 
oil in the distillate that can no longer be termed gasoline, when 
kerosene is distilled from the retort. 

The following descriptions of gasoline and kerosene by B. L. 
Smith, State Oil Inspection Chemist of North Dakdta, gives a 
definite idea of their properties and the requirements of the law 
in their regulation and sale. 

'^Gasoline is formed by the condensation of vapor that passes off at 
comparatively low temperatures during the distillation of crude petro- 
leum. It has been common practice among refiners to collect as 'straight' 
gasoline all that distillate having a specific gravity above 60°Be. At 
present, the name applies broadly to all the lighter products of petroleum 
above 50°Be. in gravity, including products obtained from the 'casing- 
head' gases of oil wells, by methods of compression and cooling, and 
also the ^cracked' gasoline formed by the decomposition of heavier 
oils when subjected to high temperature and pressure. 

^'It has been the custom to grade and sell gasoline according to 
'high' or low' gravity test. Recent study and investigation has 
shown that specific gravity in itself is of very little value in deter- 
mining the quality of a gasoline. It may be taken as an index of other 
properties, particularly its volatility, if information as to its source 
and method of production are at hand; but under present market 
conditions a specific-gravity determination is entirely inadequate. 
The specific-gravity test alone may give a high rating to a poor gasoline 
and a low rating to a good one. It has been discarded as a standard 
of comparison by the U. S. Bureau of Mines. It indicates nothing 
definite about the quality of a gasoline and in many cases it does not 
even approximate relative values. Volatility, that is, the ease with 
which it vaporizes, is the fundamental property that determines the 
grade, quality, and usefulness of gasoline. The Beaum6 test, however, 
must remain the standard for grading gasolene until a more definite 
measure is adopted. 

''The Oil Inspection Law (1917) for the State of North Dakota, 
states, that : 'all gasolines, sold or offered for sale in this State for house- 
hold use, shall, when one hundred cubic centimeters are subjected to 
a distillation in a flask— as described for distilling of oil — show not 
less than three (3) per cent, distilling at one hundred and fifty-eight 
(158) degrees Fahrenheit, and there shall not be more than six (6) 
per cent, residue at two hundred and eighty-four (284) degrees Fahren- 



262 MECHANICS OF THE HOUSEHOLD 

heit, which shall be known as the chemical test for gasoline sold or 
offered for sale in this State for domestic purposes.' 

"Gasoline for household purposes, as for use in cold-process lighting 
systems should contain not more than a very slight amount of constitu- 
ents that do not vaporize readily. It is obvious that a gasoline for 
cleaning or drying purpose should contain no oily or kerosene distillate. 
On the other hand, the gasoline for use in a gasoline stove or other 
generator, where heat is employed in its vaporization, may contain a 
considerable amount of the less volatile oils. The amount of gasoline 
sold for household use is in very minor proportion to the immense 
quantity used for motor purposes. 

"No hard and fast line differentiates good motor gasoline from 
bad. In fact standards of quality seem to be varying with advances 
in engine design, so that what once was poor gasoline can now be 
successfully used. Improvement in carburetors seem to be keeping 
pace with the ever increasing amount of kerosene in the ordinary motor 
gasoline. 

"Gravity test cannot be relied upon as indicating the kerosene 
content. In the laboratories of the Oil Inspection Department for 
the State of North Dakota, there have been examined two gasolines 
of the same gravity, 56.2°Be. at 60°F., but which contains 31 per cent, 
and 62 per cent, of kerosene respectively, and their distillation range 
is quite different. On the other hand, there are other gasolines whose 
boiling range is nearly parallel and similar, yet whose gravities are 50.2° 
Be. and 59.2°Be. respectively. Also a gasoline and a kerosene having 
a difference in gravity of but VB6. and a difference of nearly 100°F. 
in the temperature at which they begin to boil and a difference at 200°F. 
in the temperature at which all had distilled over. The so-called low'- 
test gasolines average between 35 per cent, and 40 per cent, kerosene. 
The chief element of advantage in the so-called 'high '-test gasolines 
seems to be that they yield a maximum efficiency over a larger range of 
engine conditions. 

"We have a sample of gasoline sold as 'high'-test gasoline which 
contains 29 per cent, of kerosene. Indeed it has a high Beaume gravity 
(63.70) compared to the average low-gravity gasolines on the market, 
and it also contains a large amount (14 per cent.) of very easily volatile 
constituents. Such a product seems to be a blend of very light 'casing- 
head' stock with kerosene of low boiling range to give the 'high' gravity. 

"It is desirable that a gasoline should contain a certain percentage 
of very low-boiling constituents, so that engines may start more readily, 
especially in unfavorable conditions of weather or climate; but a large 
proportion would be undesirable because of loss through evaporation 



GASEOUS AND LIQUID FUELS 263 

and the liability of accidental ignition and explosion. A reasonable 
amount of light volatile material would probably be about 33^ per cent. 
Again a reasonably low percentage of the very less volatile constituents 
is desirable to insure complete vaporization at a not too high tempera- 
ture, say not more than 10 per cent.; but such a gasoline would be ex- 
pensive. The producers and refiners claim that the present immense 
demand necessitates the mixture of low-boiling kerosene constituents 
with the true gasoline fraction. 

"Kerosene. — The character of this fuel is best understood by compar- 
ing it with gasoline, which it in general resembles, except that it is much 
less volatile. It is obtained from crude petroleum at a temperature 
just above that (300°F.) at which gasoline passes off. Its chief use is 
as an illuminant in lamps. It is also increasingly used as a fuel in 
cooking stoves, small portable heaters, and as a motor fuel for engines 
and tractors. 

^^The laws of most States stipulate certain tests which kerosene must 
meet in order to be approved for general sale. These tests include 
color, flash point, fire test, sulphur determination, and candlepower 
tests. The North Dakota Oil Inspection Law (1917) specifies that 
the color shall be water-white when viewed by transmitted light through 
a layer of oil 4 inches deep. It shall not give a flash test below 100°F. 
and shall not have a fire test below 125°F. Such illuminating oils shall 
not contain water or tar-like matter, nor shall they contain more 
than a trace of any sulphur compound. The photometric test, when 
burning under normal conditions, shall not show a fall of more than 
25 per cent, in candlepower in a burning test of not less than 6 hours 
nor more than 8 hours^ duration, consuming 95 per cent, of the oil. 

^^The flash point of an oil is the lowest temperature at which vapors 
arising therefrom ignite, without setting fire to the oil itself, when a 
small test flame is quickly approached near the surface in a test cup 
and quickly removed. 

'^The fire test of an oil is the lowest temperature at which the oil 
itself ignites from its vapors and continues to burn when a test flame 
is quickly approached near its surface and quickly removed. 

^'When oils containing sulphur are burned, the sulphur is thrown 
off in the form of gaseous sulphur compounds. Because of their 
poisonous nature and their bleaching and disintegrating action on 
clothing, hangings, wall coverings, etc., it is obvious that to safe- 
guard the health and preserve the furnishings of the home, illuminating 
oils should contain not more tlian a trace of sulphur compounds, and 
that their flash and fire limits should be high enough to insure safety 
in ordinary use in lamps and stoves. 



264 MECHANICS OF THE HOUSEHOLD 

^^The law further specifies as to the boiling limits of kerosene: 'It 
shall be the duty of the State Oil Inspector ... to have chemical 
tests made . . . demonstrating whether or no such oils contain 
more than 4 per cent, residue after being distilled at a temperature of 
570°F., and shall not contain more than 6 per cent, of oil distilling at 
310°F., when one hundred cubic centimeters of the oil is distilled from 
a side-neck distilling flask' of certain specified dimensions. 

'^This is to insure the kerosene against an excess of easily inflam- 
mable material of the gasoline range and thus render it dangerous to 
the user. In addition it is to insure against an undue proportion of 
heavy constituent of lubricating oil distillate, which would clog the wick 
and reduce the efficiency, heating and illuminating value of the oil.'' 

LIGHTING AND HEATING WITH GASOLINE 

The extended use of gasoline as a lighting and heating agent, 
has brought about the development of a great number of me- 
chanical devices that are intended to furnish the house with an 
efficient source of illumination and at the same time provide 
the kitchen with a convenient and relatively inexpensive fuel. 
These machines are generally simple in mechanical construction 
and so designed as to eliminate most of the dangers involved 
in the use of gasoline. In operation, they require a minimum 
amount of attention when suited to the purpose for which they 
are intended. That the object of the plants is attained is attested 
by the great number in use and the degree of satisfaction afforded 
the users. 

The three systems of gasoline lighting referred to above are 
known commercially by terms which are characteristic of the 
process involved: 

1. The cold'process system, in which the gasoline is vaporized, 
at the temperature of an underground supply tank, and after 
being mixed with the required amount of air is sent through the 
building in ordinary gas pipes exactly as in the case of city gas. 

2. The hollow-wire system, in which the gasoline is sent from 
the supply tank to the burners in a liquid form, where it is vapor- 
ized by heat and the vapor mixed with the necessary air to 
afford complete combustion. 

3. The central-generator or tube system, in which the gasoline is 
sent to a central generator from a supply tank and there vapor- 



GASEOUS AND LIQUID FUELS 265 

ized by heat, at the same time being mixed with air in sufficient 
amounts to render it a completely combustible gas without 
further dilution. 



THE COLD-PROCESS GAS MACHINE 

The gas machine of the cold-process type is so constructed that 
air is forced through a tank or carburetor, containing gasoline 
and remains in its presence until saturated with gasoline vapor. 
This saturated air is afterward diluted with additional air, to 
produce a quality of gas that contains proportions of air and gaso- 
line vapor which will produce complete combustion when burned 
with an open flame. 

Combustion is a rapid chemical change in which heat is evolved 
due to the union of carbon and oxygen. If the carbon is 
completely oxidized, the combination produces carbon dioxide 
(CO 2) and the greatest amount of heat is evolved. 

Gasoline being a highly volatile liquid will vaporize at tem- 
peratures as low as — 10°F., but as the temperature is higher 
vaporization will be more rapid. In a confined space, at rela- 
tively low temperature, such as the carburetor of a gas machine, 
the vaporization will at first be very rapid; but after the more 
highly spiritous portion has been evaporated, a considerable 
part, even of the lighter grades, will be vaporized very slowly. In 
the cold-process machines, only the lighter grades can be used 
with success and even then, in inefficient machines, a portion of 
the lesser volatile gasoline will have to be thrown away. For 
this reason and for others that will appear later, it is advisable to 
consider very closely the working properties of the entire plant. 

In order to obtain gas that will always be of the same quality 
and at the same time use gasoline in an efficient manner, the gas 
machine must be composed of three essential parts: the blower, 
the carburetor and the mixer. 

The blower is that part of the machine which supplies air for 
absorbing the gasoline vapor and maintaining a constant pressure 
on the system. It is usually made in the form of a rotary pump, 
the motive power for which is a heavy weight. The pump may, 
however, be driven by water pressme furnished by city \vat(M* 
pipes or other water supply. 



266 



MECHANICS OF THE HOUSEHOLD 



The carburetor is a tank which contains the supply of gasoHne 
and is so constructed as to permit the air from the blower to 
most readily take up the gasoline vapor. It should be so ar- 
ranged that when the contained gasoline becomes old and less 
volatile, the air may remain in its presence a sufficient time to 
become saturated by slow absorption. 

The mixer is that part of the machine which regulates the 
amount of gasoline vapor contained in the gas entering the dis- 




Carburetter 

Fig. 183. — Cold-process system of gasoline lighting with kitchen range and water 

heater. 



tributing pipes. In order to satisfactorily perform its function, 
it should be so arranged as to permit a constant amount of gaso- 
line vapor to enter the mixture which composes the finished 
gas. This amount should be such as to produce a bright clear 
flame in an open gas jet. If the gas contains too great an amount 
of gasoline vapor, the flame will smoke. If too little gasoline 
vapor is present, the flames will be pale and lacking in heat. 

In Fig. 183, the entire plant is shown in place. It occupies 
a place inside the building, usually in the basement. In the 



GASEOUS AND LIQUID FUELS 



267 






|^%-^(5) 



figure the carburetor is marked 1 ; the mixer 2 stands at the end 
of the blower, which is numbered 3. The motive power of the 
blower is furnished by a heavy weight, which is raised by a 
block and tackle, the cord of which is attached to the drum and 
fastened to the shaft of the blower. The force furnished by 
the weight 4 drives the blower and maintains a constant pressure 
on the gas in the system. The pipe 8 conducts the air from the 
blower to the carburetor, which is located underground, below 
the frost line and 25 or 30 feet away from the building. 

The carburetor in this case is also the storage tank, as shown 
in detail in Fig. 184. The carburetor is divided laterally into 
two or more compartments, de- 
pending on the size of the plant 
to be accommodated. That 
shown in Fig. 184 contains four 
compartments and is intended 
for a large plant. The construc- 
tion is such that the compart- 
ments are only partly filled with 
gasoline, and arranged to per- 
mit the air from the blower, 
which enters at the pipe marked 
air, to pass through each com- 
partment in succession, begin- 
ning at the bottom, in order 
that it may become completely 
saturated with gasoline vapor. 

As an additional means of aiding the saturation of the passing 
air, the compartments in this carburetor are provided with spiral 
passages through which the air must pass,, so that when it 
reaches the outlet pipe, marked gas, the air is completely filled 
with gasoline vapor. 

The vapor-saturated air now leaves the carburetor by pipe 9, 
in Fig. 183, and enters the mixing chamber 2, where it is mixed 
with the required amount of atmosphoiic air, to make it com- 
pletely combustible when burned at the burner. 

The mixing chamber is shown in detail in Fig. 185. The 
mixing is done automatically and the quahty of the gas is 




Fig. 



184. — Carburetor for cold-proc- 
ess gasoline lighting plant. 



268 



MECHANICS OF THE HOUSEHOLD 



Gas Outlet 



Movable Adjusting 
Weight 



uniform, regardless of the varying conditions of the attending 
temperature and the quaUty of the gasoUne in the carburetor. 

The vitally improtant feature of any gas machine is, that a 
constant amount of gasoline vapor be carried to the burners. If 
the gas contains too great an amount of gasoline vapor, a smoky 
flame will be the result; if an insufficient amount of gasoline 
is present, the flame will be pale and give out little light. When 
freshly charged, the gasoline in the carburetor will vaporize very 
readily, and a large amount of air must be added to the gas to 
reduce it to the proper consistency; but from old gasoline, which 
has lost most of the highly volatile matter, a smaller proportion 

of atmospheric air will be de- 
manded. For this reason, a 
mixing regulator that will 
always deliver gas containing 
the same amount of gasoline 
vapor is necessary to give satis- 
factory service. The mixer 
shown in Fig. 185 accomplishes 
this office by reason of the 
specific gravity of the gas. 

As the air in the carburetor 
takes up gasoline vapor, its 
specific gravity is increased 
Aix iniet-^ jy until the air is saturated; and 

.^'''- 185.-Diagram illustrating the j^y adding the amount of at- 

mixer of the Detroit cold-process system . 

of gasoline lighting. mosphcnc air necessary for 

complete combustion the weight 
is reduced to a definite amount which will be constant. The 
required mixture will, therefore, always weigh the same amount. 
The principle on which this mixer works is that described in 
physics as the principle of Archimedes: ^Hhat a body immersed 
in a fluid will lose in weight an amount equal to the liquid dis- 
placed.'^ In the application of the law, the gas in the mixer is 
the fluid, and the float — to be described — is the displacing body. 
The mixer in Fig. 185, is shown cut across lengthwise. The 
outside casing is indicated by the heavy black lines. The gas 
which leaves the opening at the top — marked gas outlet — is a 
mixture of gasoline and air that may be used for exactly the same 




InJet 



Observation 
Port 



GASEOUS AND LIQUID FUELS 269 

purpose and in the same manner as coal gas. It may be used 
in open-flame gas jets or in the mantle gas lamps for lighting 
purposes and also as fuel gas for domestic heating. The gas is 
distributed through the building in ordinary gas pipes which are 
installed as for any other kind of gas. In Fig. 183 the dis- 
tributing pipes are indicated by the heavy lines. 

The valve in the air inlet, in the bottom of the mixer, controls 
the amount of air to be admitted. The entering gas from the 
carburetor being heavier than the desired mixture, will raise the 
float and in so doing will open the air valve and allow the air 
from the blower to enter. The float and valve are so adjusted 
that the desired mixture is attained when the balance beam is 
level. Any variation in the mixture will change its weight and 
the valve corrects the change whether it be too much or too little 
air. 

The openings at the bottom, marked gas inlet and air inlet, 
are intended for the admission of the saturated vapor from the 
carburetor, and the atmospheric air, as required. The float 
which fills the greater part of the inner space is a light sheet- 
metal drum, that is tightly sealed and nicely balanced by a 
counterweight on the opposite end of the supending bar. The 
counterweight is made adjustable by the device marked movable 
adjusting weight — in the drawing — which permits the quantity of 
entering gas to be slightly changed as the gasoline in the 
carburetor grows old. 

The adjustment of the counterweight to suit the gas given 
off from old gasoline in the caburetor, and the occasional rewind- 
ing, to elevate the blower weight, is practically all the attention 
this plant requires. It is a real gas plant which gives every 
service that may be obtained from coal gas. 

THE HOLLOW-WIRE SYSTEM OF GASOLINE LIGHT- 
ING AND HEATING 

The hollow-wire system of gasoline lighting possesses the 
advantage of simplicity in construction and ease of installation 
that makes it attractive, particularly for use in small dwellings. 
The ease with which plants of this character are installed in 
buildings already constructed and its relatively low cost has 



^70 



MECHANICS OF THE HOUSEHOLD 



made it a popular means of lighting. The same principle as that 
used in the hollow-wire system is applied to portable gasoline 
lamps in which a remarkably convenient and brilliant lamp is 
made to take the place of the customary kerosene lamp. Small 
portable gasoline lamps are now extensively used for the same 
purpose as ordinary oil lanterns. These lamps are convenient 
as a source of light, make a handsome appearance and are rela- 
tively inexpensive to operate. 

The hollow-wire system as commonly employed is illustrated 
in Figs. 186 and 187. In the gravity type of the system as 




Fig. 186. — Hollow-wire system of gasoline lighting with gravity feed. 

illustrated in Fig. 186, the supply of gasoline is stored in the 
upper part of the house in a tank T and conducted to the burners 
below, through a system of small copper tubes as indicated by 
the heavy lines in the drawing. The same tank is used to supply 
the gasoline for the stove S in the kitchen and the lamps L in 
the different apartments. The gasohne supply in this case, is 
obtained entirely by gravity. This type of plant is not approved 
by the National Board of Underwriters but its use is quite 
generally permitted. The storage of gasoline in this form should 
be done with caution as carelessness or accident might lead to 



GASEOUS AND LIQUID FUELS 



271 



serious results. With an arrangement of this kind the force of 
gravity gives the pressure which supphes the burners below but 
it would not be possible to use the lamps on the same floor 
with the tank. 

Where it is desired to use lamps on both floors, a pressure 
tank is employed for supplying the gasoline to the lamps, as indi- 
cated in Fig. 187. In this plant the pressure tanks S, T in the base- 




FiG. 187. — Hollow-wire system of gasoline lighting with pressure-tank feed. 



ment, furnish the pressure which forces the supply of gasoline 
through the small tubes to the lamps L in the different rooms 
and also to the stove R in the kitchen. 

The means of furnishing the pressure for supplying the gasoline 
to the burners may be a simple tank as that in Fig. 188, or the 
more elaborate apparatus shown in the double tank of Fig. 189. 
Either style will give good results but the double tank requires 
the least attention in operation and is therefore more satisfactory 
in use. 

The tank in Fig. 188 is made of sheet metal of such weight as 



272 



MECHANICS OF THE HOUSEHOLD 



will safely withstand the pressure necessary in its use. It is 
arranged with an opening E, for filling with gasoline, a pressure 
gage for indicating the air pressure to which the gasoline is 
subjected, and two needle valves; C, for attaching an air pump and 
D, to which the hollow wire is attached for distributing the gaso- 
line to the places of use. The tank is filled with gasoline to 
about the line A, and then air pressure is applied with an ordinary 
air pump to say 20 pounds to the square inch. This pressure 
will be much more than will be necessary to force the gasoline 
through the tubes but it is intended to last for a considerable 
length of time. 




No.2 



No.l 



Fig. 188. Fig. 189. 

Fig. 188. — Simple gasoline pressure-tank. 

Fig. 189. — Double-pressure tank for constant pressure service in gasoline light- 
ing systems. 



The principle of operation is that known in physics as Boyles 
law, that ^Hhe temperature being constant, the pressure of a 
confined gas will be inversely as its volume.'^ That is, if the 
tank is perfectly tight, the pressure above the line A, in the tank, 
will gradually become less as the gasoline is used and when its 
level is at the line B, where the volume is twice the original 
amount, the pressure will be one-half what it was originally, 
and will still be sufficient to force the gasoline through the tubes 
to the lamps. It is evident that once the tank is charged and 
the air pressure applied it will require no further attention 
until a considerable part of the gasoline is consumed. If at 



GASEOUS AND LIQUID FUELS 273 

any time the pressure in the tank becomes too low to feed the 
lamps, a few strokes of the pump will raise it to the required 
amount. 

While the single tank does the required work, its use is not 
perfect because the pressure is constantly varying. If a lamp 
is set to burn at a definite pressure, any decrease in the gasoline 
supply due to falling pressure will change the amount of light 
given by the lamp; while the variation in the pressure of the 
single supply tank is not great, a more perfect effect is attained 
in the double type of tank as that of Fig. 189. 

The object attained in the use of two tanks differs with different 
manufacturers. The tank shown in Fig. 183, being intended to 
maintain a constant pressure on the gasoline, is quite different 
from those described in Fig. 197 in use with the central-generator 
system of lighting, to be described later. In Fig. 189 tank 
No. 1 is for air supply alone and tank No. 2 is the storage tank 
for gasoline. Between the two tanks is a pressure-regulating valve 
6-7, which keeps a constant pressure on tank No. 2 so long as the 
air pressure of the tank No. 1 is equal or greater than the other. 
The gasoline in tank No. 2 will therefore be always under the 
same pressure and when the lamps are once burning the gasoline 
supply to each lamp will be a constant amount. 

Tank No. 2 is separated by the head 13 into two compartments, 
marked 18 and 19. The connection between the two compart- 
ments is made by the valve 15 and the connection 16. The 
gasoline supply for the lighting system i§ taken from the lower 
chamber at the valve marked 17. 

It is possible to refill this tank with gasoline while the system 
is working. To accomplish this, the air supply is cut off from 
tank No. 1, by closing valve 9 and the valve 15 is closed to retain 
the pressure on the lower chamber of tank No. 2. The screw- 
plug is then taken from the tube 12 and the tank refilled. The 
screw-plug is then returned to its place, the valves 9 and 15 are 
again opened and the regulating valve immediately restores the 
desired pressure. 

The amount of pressure required on the system will depend on 
the height to which the gasoline is carried within the building. 
The pressure is generally 1 pound to each foot in height and to 
do the best work the pressure must be constant. 

18 



274 MECHANICS OF THE HOUSEHOLD 

These plants may serve as a fuel supply for gasoline stove as 
indicated at R or any other source of domestic heating. The 
usual gravity supply tank is replaced b}^ the hollow wire through 
which is the gasoline from the tank in the basement. 

Mantle Gas Lamps. — Mantle lamps that are intended for 
using city gas are much the same in construction as those using 
the cold-process gasoline gas; the styles of mechanism differ 
somewhat with manufacturers but all lamps of this kind possess 
the essential features that are common to all. Either of these 
gases may be used with open-flame burners, such as Fig. 193, but 
since the introduction of mantle lamps, the open-flame burners 
are rarely used for household illumination. 

In the incandescent-mantle lamp, the light is produced by 
heating to incandescence a filmy mantle of highly refractory 
material. The higher the temperature to which the mantle of 
a lamp is raised, the greater is the quantity of light produced. 
The office of the burner is to produce a uniform heat throughout 
the mantle with the use of the least amount of gas. As ordinarily 
furnished from the mains, coal gas or gasoline gas is too rich in 
carbon to be used in mantle lamps without dilution. When gas 
is burned in a mantle lamp, it must contain sufficient oxygen — 
which is supplied by the air — to combine completely with the 
contained carbon and reduce it to carbon dioxide. If insufficient 
air is supplied, the lamp will smoke and the mantle will soon be 
filled with soot. 

In the use of the various gases — made from coal, gasoline, 
kerosene, alcohol, etc. — as a fuel for the production of either 
heat or light, the form of the burner in which the gas is consumed 
is the most important factor of the system. Without burners 
in which to generate a satisfactory supply of heat for the desired 
purposes, mantle gas lamps would never have come into common 
use. An understanding of the mechanism of the burners of a 
system is of first importance because of the possibility of the 
failure of the entire plant through an improper adjustment of 
the lamps. 

If complete combustion of the gas is attained in the burner, 
the greatest amount of heat will be evolved and the residue 
will be. an odorless gas, carbon dioxide (CO2). If the gas is not 



GASEOUS AND LIQUID FUELS 



275 



completely burned the odor of the gas is noticeable in the air. 
Incomplete combustion may be caused by an insufficient air 
supply, which causes a smoky flame; or if a larger flame is used 
than the burner is designed to carry, some of the gas will escape 
unburned. In either case the greatest amount of heat is not 
developed by the burner. 

In most burners, whether for heating or lighting — in which 
gas, gasoline or alcohol is used as a fuel — the principle of operation 
is that of the Bunsen tube. One noticeable exception to this 
rule is the burners used with the central- 
generating systems where the Bunsen tube is 
a part of the generator. 

The gas generated from any hydrocarbon 
will burn completely, only after being mixed 
with air or other incombustible gas, in pro- 
portions such as will completely oxidize the 
carbon contained in the fuel. 

In Fig. 190 the familiar laboratory Bunsen 
burner aiffords an excellent illustration of 
the Bunsen principle which forms a part of 
all burners using gas as a fuel. The gas from 
the supply pipe issues from a small opening 
A into a tube B and by the force of its veloc- 
ity the entering gas carries into the tube 
above it a quantity of air that may be reg- 
ulated by the size of the opening. If the 
gas is burned without being first mixed with 
air, the flame will be dull and smoky but if air is admitted to 
mix with the gas, an entirely different flame is produced, the 
characteristic shape of which is shown in the figure. 

The upper part of the flame C is known as the reducing flame ; 
it is blue in color and intensely hot. The portion D is the oxidiz- 
ing flame; it is pale blue, sometimes light green in color. The 
lower part E is the gas before it begins to burn. When burning 
in air, the Bunsen flame gives scarcely any light, all of the energy 
being expended in heat. In the gas stove where the burners 
are made up of a great number of small jets, it will be seen that 
each jet shows the characteristic featiu'cs of the Bunsen flame. 

The incandescent-mantle gaslight takes advantage of the heat 




Fig. 19 0.— Cross- 
section of Bunsen bur- 
ner showing character- 
istic Bunsen flame. 



276 MECHANICS OF THE HOUSEHOLD 

generated by the Bunsen flame and produces an incandescent 
light that has revolutionized gas lighting. The flame of the 
Bunsen tube is burned inside a mantle which is rendered in- 
candescent by the heat. 

The incandescent mantle was invented by Dr. Auer von 
Welsbach and was known for a long time as the Welsbach light; 
but improvements in the process of making the mantles, brought 
other lamps of the same type on the market, when it became 
known as the mantle lamp. The first serviceable mantles were 
made in 1891 and from that time there has been a 
steady development in the gas-lighting industry. 

The original mantles were made of knitted cotton 
yarn, impregnated with rare earths and are still so 
made; but the most durable mantles are now con- 
}\ struct ed from ramie or china grass. After being 

knitted, the mantles are impregnated with thorium 
nitrate, with the addition of a small quantity of 
cerium nitrate, and occasionally other nitrates. 
The mantles are then shaped and mounted ; the fiber 
is burned out and the mantles are dipped in collo- 
dion to give them stability for transportation. When 
placed in the lamp for use, the collodion is first 
burned off and the remaining oxide of thorium forms 
Fig. 191.— ^^^ incandescent mantle. One style of mantle is 
Gas lamp now being made in which the fiber is not burned out 
mantle!^^^^ Until it is placed in the lamp. They are commonly 
used with gasoline lamps and give very good results. 
The first incandescent-mantle gas lamps to be used were of 
the upright type, such as is shown in Fig. 191, and for a long 
time they were the only mantle lamps in use. While the upright 
mantle was a great improvement over the open-flame gas jet, 
the lamp was not satisfactory because of the shadows cast by 
the flxture and from the fact that a large amount of the light was 
lost by being directed upward from the incandescent mantle. 

With the development of the inverted type, the mantle lamp 
was greatly improved. In the use of lamps of any kind, the 
desired position of the illumination is that in which the light is 
directed downward. In the inverted type of mantle lamp this 
feature is accomplished and adds materially to the efficiency of 




GASEOUS AND LIQUID FUELS 



277 



the light, because the rays are sent in the direction of greatest 
service. The upright mantle lamps are still sold but by far the 
greater number offered for sale are of the inverted type. 

The essential features of all gas lamps used under these con- 
ditions are shown in Fig. 192, which represents the common 
bracket type of lamp. The gas-cock (7, connects the lamp with 
the gas supply G, The gas escapes into the Bunsen tube, through 
an opening in the tip P, which is so constructed that the amount 
of gas may be varied to suit the required conditions. The 
brass screw nut N may be raised or lowered and thus increase or 
diminish the amount of escaping gas by reason of the position 
of the pin P. If the nut is screwed completely down the pin 
closes the opening and the gas is entirely shut off. When the 
lamp is put in place, the burner 
is adjusted to admit the proper 
amount of gas and so long as the 
quality of the gas remains the 
same, no further adjustment will 
be necessary. Any change to a 
richer or poorer gas will, however, 
require an adjustment of the 
burner to suit the mantle. The 
amount of gas admitted is only 
that which will produce complete 
combustion in the mantle when combined with the required 
amount of air. Each burner must, therefore, be designed for 
the mantle in use. 

As the gas leaves the opening above the pin P, it enters the 
mixing chamber of the Bunsen tube and air is drawn at the 
openings A-A. The mixture of the gas and air is accomplished 
in the tube leading to the mantle M, where it is burned. In 
all lamps of this kind, there is a wire screen placed relatively as 
aS, the object of which is to prevent the mixture in the tube from 
exploding — in case of low pressure — and thus cause the gas to 
ignite and burn at the point of entrance to the tube. 

At any time the pressure is insufficient to send a steady flow 
of gas into the tube, the flame may ^^ flash back'^ and ignite the 
gas at the point of entrance where it will continue to burn. If, 




Fig. 192. — Mantle gas lamp show- 
ing details of Bunsen tube. 



278 



MECHANICS OF THE HOUSEHOLD 



however, the screen is interposed between the gas supply and the 
burner, the flame of explosion will not pass the screen. 

In lighting the lamp, the gas is turned on and a lighted match 
is held under the mantle, the explosive mixture of gas and air 
fills the mantle and escapes into the globe, in which it is usually 
inclosed. As soon as ignition takes place the gas outside the 
mantle explodes with the effect that is startling but not necessarily 
dangerous. The escaping gas continues to burn and heats the 
mantle to incandescence. 

The amount of escaping gas is regulated by turning the gas- 
cock to produce the greatest brilliance with the least flame out- 
side the mantle. When used for household illumination, the 
intensity of the light is such as to be objectionable, when used 
directly; but when surrounded by an opal glass globe to diffuse 
the light, this is a highly satisfactory and economical means of 
lighting. 

Open-flame Gas Burners. — Gas jets of the open-flame type 
continue to be used to some extent but the more efficient mantle 

lamp has very largely supplanted 
lights of this kind. In the past, 
these gas lights were made in a 
great many styles and were 
known under a variety of trade 
names — the fish-tail burner, the 
bats-wing burner and the Ar- 
gand burner — and were at times 
very generally used for gas 
lighting. 

The common gas jet is illus- 
trated in Fig. 193. The figure shows a bracket fixture which 
is generally fastened to a pipe in the wall. A swing-joint at A 
permits the flame F to be moved into different positions. The 
annular opening A permits the gas to pass to the jet in any 
position to which the light is moved. The gas-cock C is a cone- 
shaped plug, which has been ground to perfectly fit its socket. 
It should move with perfect freedom, and yet prevent the es- 
cape of the gas. A slotted screw N permits the joint to be re- 
adjusted, should the plug become loose in the socket. 

The gas-tips T are made of a number of different kinds of 




Fig. 193. — Swing-bracket gas lamp 
with open-flame burner. 



GASEOUS AND LIQUID FUELS 



279 



materials and are commonly termed lava-tips but tips for gas 
and gasoline are frequently made of metal. The bottom of the 
tip is cone-shaped, which permits it to be forced into place in the 
end of the tube with a pair of pliers. In size the tips are graded 
by the amount of gas which they will allow to escape in cubic 
feet per hour. For example — a 4-foot tip will use approximately 
4 cubic feet of gas per hour. They are made in a number of sizes 
to suit the varying requirements. 

The Inverted-mantel Gasoline Lamp. — The inverted-mantle 
gasoline-gas lamp shown in Fig. 194, furnishes a good example of 
mechanism and principle of operation, when used with the hollow- 
wire system. This is the bracket style of lamp but the same 
mechanism is used in other forms of fixtures. Lamps of similar 




Fig. 194. — Sectional view of hollow-wire mantle gasoline lamp. 

construction are suspended from the ceihng, either singly or in 
clusters; they are also used in portable form. 

In Fig. 194 the lamp consists of a bracket //, which is secured 
to the wall and through the stem of which the gasoline is con- 
ducted to the generator by the pipe W, The arrows show the 
course of the gasoline and its vapor as it passes through the lamp. 
On entering the generator the gasoline first passes, the percola- 
tion, through an asbestos wick B, the object of which is to pre- 
vent the vapor pressure from acting dii-ectly on the gasoline in 
the supply tube. The gasoline passes through the wick B, 
largely by capillary action, as it must enter the generator against 
a pressure greater than that afforded by the pressure tank. The 



280 MECHANICS OF THE HOUSEHOLD 

vaporization of the gasoline takes place in the tube above the 
mantle T, from the flame of which it receives the necessary heat. 

In lighting the lamp an asbestos torch saturated with alcohol is 
ignited and hung on the frame, so that the flame may heat the 
generating casting N, This process usually requires less than a 
minute, generally about 40 or 50 seconds. The torch supplies 
heat sufficient to generate the vapor for lighting the lamp, but 
as soon as lighted the heat from the glowing mantle keeps the 
generator at the required temperature for continuous supply of 
vapor. 

When the generator is sufficiently heated by the generating 
torch, the needle valve N is opened by pulling the chain P. This 
allows the gasoline vapor from the generating tube to escape at 
G into the induction tube R. As the vapor enters the induction 
tube at a high velocity, it carries with it the atmospheric air in 
quantity sufficient to render it completely combustible. The 
opening G and the tube together form a Bunsen burner. The 
lamp is so proportioned as to give a mixture of gasoline vapor and 
air that will produce complete combustion in the mantle jT. The 
portion of the burner Z, through which the gas enters the mantle, 
is a brass tip, filled with a fluted strip of German silver, so ar- 
ranged that the gas on entering the mantle will be uniformly 
distributed and that the heat generated will render the entire 
mantle uniformly brilliant. 

One feature of the lamp that requires special attention is the 
opening (?, through which the vapor from the generator is dis- 
charged into the induction tube. This is a very small opening 
and occasionally becomes stopped or partly closed. When this 
occurs the lamp fails to receive the necessary amount of gas, 
and the light is unsatisfactory. In this lamp, the cleaning 
needle Q is provided for removing the stoppage. The needle 
is simply screwed into the opening and forces out the obstruc- 
tion; when it is withdrawn, the opening is left free. A more 
convenient device for accomplishing the same purpose is de- 
scribed in the portable lamp. Figs. 195 and 196. 

Portable Gasoline Lamps. — The portable form of desk and 
reading lamps for the use of gasoline is made in a great variety 
of styles. They are sometimes constructed to feed by gravity, 
but by far the greater- number are operated by the pressure 



GASEOUS AND LIQUID FUELS 281 

method. The portable lamp must be a complete gas plant, 
with storage tank for the gasoline, pipe system for conducting the 
gasoline to the lamp, generator and burner. To give satis- 
factory results, the lamp must be capable of being lighted with 
the least degree of trouble and operated with the least amount 
of care. The immense number of lamps of this kind that are 
sold shows that they meet all of these requirements and have 
proven satisfactory in operation. Their greatest attractiveness 
is their capability of giving a very large amount of light at 
relatively low cost. 

Fig. 195 illustrates a portable gasoline lamp in which a con- 
venient and efficient form of generating mechanism is combined 
with an attractively proportioned exterior. The 
lamp works on the principle of the hollow-wire 
system, the base serving as a storage and pressure 
tank, the frame of the lamp acting as the tube for 
supplying the lamp with gasoline, and the canopy 
containing the generating mechanism. 

The tank in the base is filled with gasoline at 
the opening E, which is made air-tight by a screw- 
plug. The plug also contains an attachment piece 
for the air pump, which furnishes the pressure to 
the gasoline. The hollow standard reaches to the 

bottom of the tank and through it the gasoline ^ ^__ 

n,,. JbiG. lyo'. — 

IS forced to the pomt marked A, where the gaso- Portable, gaso- 
line enters the generating mechanism. This part }^^® mantle 
of the lamp, which is entirely concealed by the 
lamp canopy, is shown in detail in Fig. 196. The reference 
letters in Fig. 195 apply to the same parts in the detail drawing. 
The gasoline enters an asbestos-packed tube F at the point A , 
and after percolating trough the tube, reaches the regulating 
valve at the point G. The hand-wheel B opens and closes the 
valve, and thus controls the entrance of the gasoline to the gen- 
erating tube Hj where it is converted into the vapor. The vapor 
now needs only the addition of air to make it the dosiriMl gas for 
ilUuninating the mantle. 

The vapor fi'om the generating tube escapes at the small \\o\c 
K, located direc^tly under the mixing chamber M. The supply of 
air is received through the tube C, provided with a regulator, 




282' 



MECHANICS OF THE HOUSEHOLD 



which is readily accessible from the outside of the lamp. The 
mixture of gasoline vapor and air is accomplished as in the other 
lamps described, through the Bunsen tube N, In this case, the 
Bunsen tube is extended and increased in size to produce a 
mixing chamber of considerable volume. The mantle is attached 
to the tip 0. The tip, like the one already described, is made 
of German silver and constructed to produce a flame that will 
entirely fill the mantle. 

This lamp is provided with a special means of keeping the 
opening K free from accumulations. The opening K, through 

which the gasoline vapor es- 
capes from the generator, is very 
small and a slight stoppage will 
materially interfere with the flow 
of the vapor and thus impair 
the illuminating effect of the 
light. A lever D operates an 
eccentric which engages the 
piece P, to which is attached a 
pin that readily enters an open- 
ing K, when the lever is turned. 
Any accumulation which may 
lodge in the opening is instantly 
removed and the needle re- 
turned to its place by a turn of 
the lever D, 

Central-generator Plants. — 
The central-generator or tube 
system of lighting with gasoline, 
differs from the other methods 
described, in the manner of 
generating and distributing the 
In the hollow-wire system each 
With the central-generator 




Fig. 196. — Sectional view of the 
generator for the American hollow- 
wire gasoline lamp. 



supply of gas to the lamps, 
lamp generates its own gas supply, 
system the gas for all of the lamps is generated and properly 
mixed with air in a central generator, and the finished gas dis- 
tributed through tubes to the different burners and there burned 
in incandescent mantles. The gas as it leaves the generator 



GASEOUS AND LIQUID FUELS 283 

requires no further mixing with air and therefore the burners are 
not of the Bunsen type. 

Central-generator gas machines are made in a number of 
different forms by different manufacturers, all of which are 
intended to perform the same work but differ in the mechanism 
employed. The machines are simple in construction and as in 
the hollow-wire system are capable of using lower grades of 
gasoline than can be used with the cold-process plants. The 
gas from a central generator may be used for all purposes for 
which gasoline gas is employed, either for lighting or heating. 
One difficulty in the use of the machine is the lack of flexibility 
when required for only a few lamps or varying number of lights. 
Although these plants are sometimes used for lighting and heat- 
ing dwellings, their use is limited, for the reason that variation 
of the number of lights requires the generator to be regulated 
to suit the change in the gas supply. The plants cannot be 
conveniently cut down to one light. Their most general use is 
that of lighting churches, stores, halls, auditoriums, etc., where 
a variable amount of light is not demanded. Plants of this 
character are quite generally used for street lighting and for 
other outside illumination. 

An efficient and simple plant of the central-generator type is 
shown in Fig. 197. The supply of gasoline is stored in a tank 
similar to that used with the hollow-wire system and placed in 
any convenient location. The gasoline is conducted to the gen- 
erator Gj through a hollow wire marked W, The generator is 
inclosed in a sheet-iron box, which is located at any convenient 
place in the building. From the generator the gas is conducted 
through the tube to the lamps L. 

In Fig. 198 is shown a diagram of the generator, cut through 
the middle lengthwise, in which all of the working parts are 
shown in their relative positions. The reference figures designate 
the same parts of the generator in Figs. 197 and 198. 

In the process of generation the tank is filled with gasoline 
and pressure apphed with the air pump. The tanks described 
in Fig. 189 might be used to advantage with this plant but the 
one shown in Fig. 197 is so constructed that the larger tank is 
used for storage of gasoUne. The gasoUne is pumped directly 
into the smaller tank which alone is kept under pressure. The 



284 



MECHANICS OF THE HOUSEHOLD 



pump P is enclosed in the large tank; at any time it is desired to 
replenish the supply. of gasoline, it is only necessary to open the 
valve V and pump the necessary supply into the small tank. 
This transfer may be done at any time without danger from 
escaping gasoline vapor. 

The process of generating the gas is best understood by ref- 
erence to Fig. 198, which shows the internal construction of the 



a 



^ 



^ 



^5^=^ 




Fig. 197. — Diagram of central-generator tube system of gasoline lighting. 



generator. The Uquid gasoline is admitted at the bottom 
through the small pipe TF, and then enters the space 4, where it 
is vaporized. The initial flow of gas is generated by heating 
the generator with an alcohol flame from the iron cup 1, which 
surrounds the generator. When the generator is heated the 
gasoline admitted to the generator is immediately vaporized; 
when, by turning the handle 6, the needle valve 5 opens a small 



GASEOUS AND LIQUID FUELS 



285 



^14 



15 



orifice through which the heated gasoUne vapor escapes into the 
tube 7, above. 

The blast of vapor issuing from the orifice carries with it air 
of sufficient volume to render the gasoline vapor an explosive 
mixture that when burned in the mantle will be reduced to 
CO2 gas. 

When the initial heating by the alcohol flame is exhausted, 
sufficient gas has been generated so that part of it may be used 
as a sub-flame in the gas burner 9, 
to keep the generator heated. The 
gas is conducted to the burner 
from the main tube 11, through 
the pipe 12-14, as indicated by the 
arrows. The burner 9 surrounds 
the generator and the size of the 
flame is regulated by the valve 15, 
which is opened an amount suffi- 
cient to admit the necessary gas 
to the burner. 

To start the generator, the cup 
1 is filled with alcohol and ignited. 
The needle valve 2 is now opened 
by turning the hand-wheel 3, ad- 
mitting gasoline into the generator 
chamber 4, where the vaporization 
of the gasoUne takes place. The 
flame from the burning alcohol will 
heat the generator in about a minute. When the generator is 
hot, the needle valve 5 is opened slightly, by turning the lever 
6, and the gasoline vapor under high pressure blows into the 
tube 7. As the gasoline vapor is blown into the tube 7, air is 
drawn in through the opening 8, as indicated by the arrows. 
The generator is practically a large Bunsen tube from which 
the mixture of gasoline vapor and air is conducted to the burners 
by a connecting pipe. 

Gas machines operated on this principle are made to accom- 
modate a definite number of lamps. After the lamps are lighted, 
the amount of gas is regulated to suit the number in use. If at 
any time it is desired to reduce the number of lamps in opera- 




Gasoline 



S^^^^ 



te=^-^-3 



Fig. 198. — Cross-section of the 
generator for the tube system of 
gasoline lighting. 



286 



MECHANICS OF THE HOUSEHOLD 



tion, the gas supply must be regulated to suit the lights left 
burning. 

As an illustration, suppose that a plant of ten lamps had been 
burning and that it was desired to reduce the number to six; 
four of the lamps are extinguished by turning the levers C, which 
control the gas-cocks. The generator which had been supplying 
sufficient gas for ten fights wifi continue to produce the same 
amount until the lever 6 is turned to reduce the supply of gasofine 
to the required amount for six lamps. This is done by gradually 
closing the valve 5 until the lamps again burn brightly. 

In small plants the least number of lamps that will work 
satisfactorily at one time is three. Automatic regulators are 

made for plants of consider- 
able size but do not satisfac- 
torily control the gas when the 
lamps are reduced below three 
in number. The gas from these 
plants may readily be used in 




kitchen ranges, water heaters 
and other domestic purposes. 
Individual plants for operating 
ranges in restaurants and hotels 
are in common use. The plants 
Fig. 199.— Gas lamp for use with the ^re subiect to minor derange- 

central-generator or tube system of gaso- , ,-\ , 

line lighting. ments that require correcting as 

they occur, but as soon as the 
mechanism and characteristic properties of the plant are known, 
the correction of any difficulty that may present itself is easily 
accomplished. 

Central-generator Gas Lamps. — Fig. 199 shows the general 
construction and arrangement of the parts of the inverted- 
mantle-lamp used with the central-generator System. In out- 
ward appearance the lamp is much like any other inverted-mantle 
gas lamp, but in arrangement of parts it is markedly different. 
The gas-cock C is larger than that used with the ordinary fixture, 
because the opening must carry a larger volume of gas than 
that for supplying gas to lamps using the Bunsen tube. In 
the use of lamps with the Bunsen tube, the gas from the mains 
is mixed with approximately twenty times its volume of air; 



GASEOUS AND LIQUID FUELS 



287 



with a lamp like that of Fig. 199, where the mixture has already 
been made in the generator, the conducting tubes and the gas- 
cock must be relatively very large. 

The screen aS, which corresponds to the screen 
aS in Fig. 192, is quite as necessary as in the other 
lamp. It not only assures a uniform distribution 
of the gas in the tube but it prevents the mantle 
from being broken when the burner is lighted. 
If this screen is punctured, the explosion which 
takes place when the burner is lighted will be 
sufficient to blow out the bottom of the mantle. 
The burner tip T is practically the same as that 
used with other mantle lamps. 

Boulevard Lamps. — Gasoline 
lamps for outside illumination may 
be constructed to operate with any 
of the systems described, but the 
hollow-wire and the generator 
systems are most conveniently used, 
because each post may be arranged 
as an independent plant. For illu- 
minating private grounds or public 
thoroughfares, lamps such as are 
illustrated in Figs. 200 and 201 are very generally 
used. 

The lamp shown in Fig. 200 is of the central 
generator type in which the storage tank and 
generator mechanism are located in the base of 
the post. These lamps are also sometimes con- 
structed with a time attachment in the base of the 
post, arranged with a clock mechanism so that 
the light may be automatically extinguished at 
any desired time. 

In Fig. 201 the lamp is of the hollow-wire type 
and as in the case of the other, the supply tank 
is in the base of the post. With this system 
it would be possible to supply several lamps from 
a common supply tank, provided the hollow wire was protected 
against damage. The lamps arranged to work on either system, 



Fig. 200.— 
Boulevard lamp 
with generator 
in the base of the 
lamp post. 



Fig. 201. 
Boulevard lamp 
operated by the 
hollow-wire 
method of light- 
ing. 



288 



MECHANICS OF THE HOUSEHOLD 



require the same amount of attention and are subject to the 
same derangements as those for inside service. 

Burners for gasoline stoves are made in a great variety of 
forms, each having some special points of excellence that are 
used to recommend the sale of the stove. The most essential 
feature of a gasoline stove is the burner, since on its successful 
performance will depend the satisfaction given by the stove. 
Many self -generating burners have been devised which have met 
with a great deal of favor, but the type of burner most widely 

used and the first to be de- 
vised for the purpose is the 
generating burner similar in 
principle to the generating 
gasoline lamp. 

The burner is first heated 
from an outside source, in 
order to generate sufficient 
gas to start the flame, after 
which the heat from the 
burner will develop the gas 
supply. With gasoline stoves 
of this kind, the supply tank 
is elevated, in order that the 
force of gravity may give 
sufficient pressure to send 

Fig. 202.— Sectional view of the generator the gasoline iuto the genera- 

and burner of a gasoline stove. ^or while the flame is burn- 

ing. In the hollow- wire 
system the same type of burner is used, but the gasoline is forced 
into the burner by the pressure in the tank. 

In Fig. 202 is shown a sectional view of the burner as it appears 
in the stove. The supply tank, or hollow wire from the pressure 
tank, sends the gasoline into the tube A at the bottom of the 
stove, to which several burners may be attached. The tube B, 
through which the gasoline percolates on its way to the generator, 
is filled with moderately coarse sand, or other material that is 
intended to prevent the gasoline from being forced out of the 
pipe by the pressure that is developed in the generator. The 




GASEOUS AND LIQUID FUELS 289 

pieces C-C are perforated metal plugs that prevent the escape 
of the particles of which B is composed. 

The generator is a brass casting D-D which is firmly screwed 
to the top of the tube B. A needle-valve E governs the discharge 
of the gasoline vapor at G, where the vapor enters the tube Hj as 
indicated at K-K, The gasoline vapor enters the open Bunsen 
tube Hy and with it is carried the air necessary to produce the 
required gas for complete combustion. The piece N is the 
generating cup in which is burned the generating fluid — either 
gasoline or alcohol. The gasoline from the pipe A percolates 
through the material in B and flows into the generator. The 
needle- valve being closed, the space D-D fills with gasoline. 

To light the burner, the hand-wheel J is turned, opening the 
needle-valve a sufficient length of time to allow the gasoline to 
fill the cup N with fuel for generating the initial volume of vapor. 
A still better way is to fill the cup with alcohol, because the burn- 
ing alcohol does not fill the air with smoke and odors, as in the 
case of gasoline, when used for generating purposes. The 
generating material having been ignited and burned out, the 
generator is hot and filled with vapor. The heated generator 
vaporizes a portion of the contained gasoline and forms sufficient 
pressure to force the remaining gasoline back through B into the 
supply tank. The material of the tube B permits only a slow 
movement of the gasoline and prevents the possibility of surging 
in the generator. 

The initial supply of vapor being generated, the needle-valve 
may be opened and the gas lighted above the burner 7-7, where 
it should burn in little jets at each opening with the characteristic 
Bunsen flame. It sometimes happens that the generator is not 
heated sufficiently, by the generating flame, to vaporize the 
necessary gasoline for starting the burner; in this case liquid 
gasoline will be forced from the opening (?, and the burner will 
flare up intermittently in a red smoky flame. When this occurs 
the burners must be regenerated. 

Gasoline Sad Irons. — The use of gaseous or liquid fuel is always 
attended by an element of danger, because of the possibility of 
accidental explosion. The use of gasoline, the most highl}^ 
volatile of all liquid fuels, has, however, come to be very 
generally used as a source of heat for domestic purposes. The 

19 



290 



MECHANICS OF THE HOUSEHOLD 



danger of accident in the use of gasoline as a fuel for heating 
sad irons is largely due to ignorance of the involved mechanism 
or carelessness in manipulation. A knowledge of the principle 
included in their operation, together with an observance of the 
possible cause of accident, will reduce the element of danger to 
a negligible quantity. 

The use of gasoline sad irons has come into favor because of 
their convenience and economy in operation. These irons, in 
common with the use of gasoline in its other applications of 
heating and lighting, are made in a great many forms but the 
principle of operation is confined to two types. 





Fig. 203. — Gasoline flat-iron oper- 
ated by a heated fuel tank. 



Fig. 204. — Gasoline flat-iron show- 
ing the position of the cover while 
initial charge of gas is being generated. 



First, those in which the gasoline is forced into the generator 
by the vapor pressure, from the heated supply tank; and second 
those in which the pressure is caused by pumping air into the 
supply tank after the manner of the hollow-wire system of 
lighting. 

The first type of iron is illustrated in Fig. 203. The same iron 
is shown in Fig. 204, with the top in position for generating vapor 
pressure necessary to start the burner. The body of the iron A 
is a hollow casting, designed to receive the generator and burner 
in such position that the bottom portion of the iron may be 
uniformly heated. The generator and burner are shown in 
detail in Fig. 205, in which a sectional view is given of the parts, 
cut across lengthwise of the iron. 

In starting the burner for use, the tank is first filled — not quite 
full — of strained gasoline. The precaution of straining the gaso- 



GASEOUS AND LIQUID FUELS 



291 



line should be taken, to prevent putting into the tank anything 
that will possibly choke the needle-valve. Alcohol is used for 
generating the vapor supply, because the flame does not black 
the iron and fill the room with smoke as in the case when gasoline 
is used for the purpose. When the alcohol is ignited, the cover 
is placed in position as shown in Fig. 204, so that the flame may 
heat not only the generator but also the tank. The object of 
heating the tank is that the heated gasoline may furnish pressure 
with which to force the gasoline into the generator. When the 
alcohol used for generating is almost burned out, the valve F is 
slightly opened and the burner lighted. 

As shown in Fig. 205, the generator G is a brass tube, inclosing 
the valve-stem G, which terminates in the needle-valve F. This 




Jidb^jUbiibdidlidbdUJ^^ 



Fig. 205. — Sectional view of gasoline flat-iron generator and burner. 

valve regulates the supply of gas admitted to the burner and is 
operated by the hand-wheel F. When the gasoline in the tank 
has been heated the necessary amount, the vapor in G is allowed 
to escape through the valve V. The vapor is discharged into 
the Bunsen tube, and with it the air is carried in through the 
openings E, from both sides of the iron. The burner is a brass 
tube, slotted as shown at H, through which the gas escapes, 
forming a short flame of large area close to the part of the iron 
to be heated. The size of the flame is regulated by the hand- 
wheel F. 

The tank is entirely closed, the plug P being provided with a 
lead washer to insure a tight joint. The plug is further provided 
with a soft metal center which acts as a ''safety-plug" in case of 



292 



MECHANICS OF THE HOUSEHOLD 



overheating. Should the iron at any time become too hot, the 
soft metal center will melt and the released pressure in the tank 
will put out the burner flame. The soft metal center may be 
renewed with a drop of solder. In case the safety-plug at any 
time is melted, the hot gasoline will spurt from the opening and 
immediately vaporize. This of course would, in a short time, 
produce an explosive atmosphere which if ignited would be 
dangerous. In case of accident the iron should be carried to the 
open air and the flame smothered with a cloth. 

Alcohol Sad Irons. — Irons of the same style are also made in 
which alcohol is used as a fuel. The alcohol irons differ in con- 
struction from those using gasoline only in the amount of air 

that is mixed with the vapor. In 
general appearance the two styles 
look very much alike, but in the 
alcohol iron one of the intakes E 
is entirely closed and the other 
opening is partially closed. 

The operation of these irons is 
identical to those using gasoline, 
but they are preferred by those who 
fear the use of that fuel. In reality 
there is little difference in the 
danger attending the use of the 
two liquids. It is only fair to say, 
however, that the use of any highly 
volatile fuel is attended with some danger when used carelessly, 
but with a reasonable amount of care and a knowledge of the 
mechanism of the machine in use the danger is of minor 
consequence. 

In Fig. 206 is illustrated another style of gasoline sad iron, the 
working principle of which is the same as those already described 
but the supply tank is not heated to give pressure to the gasoline 
in the tank. In this iron the tank is located at one side of the 
iron and pressure is applied with an air pump as in the hollow- 
wire system of lighting. The burner is generated after the 
manner of the others and operated in exactly the same manner. 
The chief difference is that the possibility of excessive pressure 
through overheating is eliminated. 




Fig. 206. — Gasoline flat-iron oper- 
ated by an air-pressure fuel tank. 



GASEOUS AND LIQUID FUELS 



293 



Alcohol Table Stoves. — In the United States the use of alcohol 
as a fuel has never been extensively employed because of the 
duty imposed on its manufacture by the Federal Government. 
In 1896 this duty was removed from denatured alcohol and the 
cost was sufficiently reduced 
to permit a great extension 
in its use as a fuel. 

Denatured alcohol is any 
alcohol to which has been 
added any of the list of pre- 
scribed volatile fluids that will 
render the alcohol unfit for 
use in beverages and not ma- 
terially change its heating 
value. Denatured alcohol is 
sold at a price that will per- 
mit its use in small flat-irons, 
table stoves and other forms of 
burners where small amounts 
of heat are generated for con- 
venience. At the price of denatured alcohol as generally sold, 
it cannot compete with gasoline and kerosene as a fuel. 

In Fig. 207 is shown a convenient and inexpensive form of 
table stove, in which the vapor of alcohol is burned in practically 
the same manner as the vapor of gasoline in the burners already 
described. The supply of alcohol is stored in a tank A, and fed 




Fig. 207. — Alcohol vapor stove. 




Fig. 208. — Sectional view of the generator and burner of the alcohol vapor stove. 

by gravity to the burner 5, the flame from which resembles that 
of the ordinary gasoline burner. 

The generator G with the other essential parts are shown in 
detail in Fig. 208. The reference letters indicate the same parts 
in the detail drawing as in Fig. 207. 

The alcohol flows from the supply tank through the pipe C to 
the generator G, which is a brass tube filled with copper wires. 



294 MECHANICS OF THE HOUSEHOLD 

The vapor for starting the burner is generated by opening the 
valve V and allowing a small amount of alcohol to flow through 
the orifice C into the pan P directly below the generator. The 
valve is then closed and the alcohol ignited. When the generat- 
ing flame has burned out, the valve V is again opened and the 
vapor which has generated in the tube escapes at the orifice C 
and enters the Bunsen tube T, (Fig. 207) carrying with it the 
proper amount of air to produce the Bunsen flame at each of the 
holes of the burner. 

As in the case of the gasoline burners the orifice C sometimes 
becomes clogged and it is necessary to insert a small wire to clear 
the opening. With the stove is provided a tool for this purpose. 
With stoves of this kind, the supply tank must not be tightly 
closed, because any pressure in the tank would cause it to become 
dangerous. The alcohol is fed to the generator entirely by 
gravity. The stopper of the tank contains a small hole at the 
top which should be kept open to avoid the generation of pressure 
should the tank become accidentally heated. 

Stoves of this kind may be conveniently used for a great variety 
of household purposes, and when intelligently handled are rela- 
tively free from danger. 

Danger from Gaseous and Liquid Fuels. — All combustible 
gases or vapors, when mixed within definite amounts, are explo- 
sive. The violence of the explosion will be in proportion to the 
volumes of the gas and the condition of confinement. 

When gasoline or other volatile fuel is vaporized in a closed 
room, there is danger of an explosion, should the mixture of the 
vapor and air reach explosive proportions. It is dangerous to 
enter a room with a lighted match or open-flame lamp, where 
gaseous odor is markedly noticeable. In case of danger of this 
kind the windows and doors should be immediately opened to 
produce the most rapid ventilation. 

In the act of igniting the flame in a gas or vapor stove, the 
lighter should be made ready before the gas is turned on. Ex- 
plosions in gas and vapor stoves are usually due to carelessness 
in igniting the fuel. It should be kept constantly in mind that, 
if a combustible gas is allowed to escape and mix with air in 
any space and then ignited, an explosion of more or less violence 
is sure to occur. 



GASEOUS AND LIQUID FUELS 295 

Gasoline and kerosene are lighter than water and will float on 
its surface. The flames from these oils are aggravated when 
water is used in attempting to extinguish them. The burning 
oil floating on the surface of the water increases the burning 
surface. 

Burning oil must be either removed to a place where danger 
will not result or the flames must be smothered. In case of a 
small blaze, the fire may be extinguished with a cloth, preferably 
of wool, or if circumstances will permit, with ashes sand or earth. 

Alcohol dissolves in water and may, therefore, be diluted to a 
point where it will no longer burn. 

ACETYLENE-GAS MACHINES 

Acetylene is a gas that is generated when water is absorbed 
by calcium carbide, after the manner in which carbonic acid gas 
is evolved when lime slakes with water, but with the liberation 
of a larger amount of the combustible gas. 

Calcium carbide is a product resulting from the union of lime 
and coke, fused in an electric furnace to form a grayish-brown 
mass. It is brittle and more or less crystalline in structure and 
looks much like stone. It will not burn except when heated with 
oxygen. A cubic foot of the crushed calcium carbide weighs 
160 pounds. 

Calcium carbide — or carbide as it is ordinarily termed — may 
be preserved for any length of time if kept sealed from the air, 
but the ordinary moisture of the atmosphere gradually slakes it 
and after exposure for a considerable time it changes into slaked 
lime. The carbide itself has no odor, but in the air it is always 
attended by the penetrating odor of acetylene, because of the gas 
liberated by the moisture absorbed from the air. 

If protected from moisture, calcium carbide cannot take fire, 
being like lime in this respect; it is therefore a safe substance to 
store. It is transported under the same classification as hard- 
ware, and will keep indefinitely if properly sealed. 

A pound of pure carbide yields 5I2 cubic feet of acet^dene, but 
in commercial form, as rated by the National Board of Fire 
Underwriters, lump carbide is estimated at 4} 2 cubic feet per 
pound. In the generation of acetylene, exact weights of carbide 



296 MECHANICS OF THE HOUSEHOLD 

and water always enter into combination, i.e., 64 parts of carbide 
to 34 parts of water, and a definite amount of heat is evolved for 
each part of carbide consumed. 

Uncontrolled, the gas burns with a bright but not brilliant 
flame and with a great deal of smoke, but when used in a burner 
suited for its combustion it burns with a clear brilliant flame of a 
quality approaching sunlight. While carbide is not explosive 
nor inflammable, it may, if it finds access to water, create a 
pressure such as to burst its container, and it is not impossible 
that heat might be generated sufficient to ignite the gas under 
such conditions. That such condition would often occur is not 
at all probable. When water is sprinkled upon carbide, in 
quantity such that it will all be taken up, the resultant slaked 
lime is left dry and dusty, and occupies more space than the 
original carbide. When more than enough water is employed, 
the remaining mixture of lime and water is whitewash. 

Chemically considered, acetylene is C2H2; it is composed of 
carbon and hydrogen and belongs to a class of compounds known 
as hydrocarbons, represented in nature by petroleum, natural 
gas, etc. It is composed of 92.3 per cent, carbon and 7.7 per 
cent, of hydrogen, both combustible gases. It is a non-poison- 
ous, colorless gas, with a persistent and penetrating odor. Its 
presence in the air, to the extent of 1 part in 1000 is distinctly 
perceptible. When burning brightly in a jet, there is no per- 
ceptible odor. When completely burned it requires for its com- 
bustion 23^^ times its volume of oxygen. 

All combustible gases, when mixed with air and ignited, pro- 
duce more or less violent explosions. Acetylene is no exception 
to the rule, and when allowed to escape into any enclosed space 
it will quickly produce a violently explosive mixture, so that it is 
always dangerous to enter a room or basement with a lamp or 
flame of any kind where the odor of gas is perceptible. This is 
quite true with a combustible gas of any kind, but with acetylene 
all mixtures from 3 to 30 per cent, are capable of being exploded 
with greater or less violence. 

The kindling point of acetylene is lower than coal gas or 
gasoline gas. To ignite either of the latter gases, a flame is 
necessary to start the combustion, but a spark or a glowing cigar 
is sufficient to ignite acetylene. It should therefore be borne in 



GASEOUS AND LIQUID FUELS 297 

mind that acetylene is not only explosive when mixed with air 
but that it is very easy to ignite. Under ordinary pressures 
pure acetylene is not explosive, but at pressure above 15 pounds 
to the square inch explosions sometimes occur where proper pre- 
cautions are not observed. At all pressures such as are required 
for household purposes acetylene is as safe for use as any other 
gas. 

Although acetylene is in danger of exploding when under 
pressure, it is perfectly safe, when the proper conditions are 
observed, in tanks for a great many kinds of portable lights. 

Where acetylene is used in portable tanks under pressure, 
advantage is taken of its solubility in acetone. This is a product 
of the distillation of wood which possesses the property of ab- 
sorbing acetylene to a remarkable degree. In addition to this 
property is the more important one of rendering the acetylene 
non-explosive when under pressure. The tanks for its storage 
are filled with asbestos or other absorbent material that is 
saturated with acetone. The acetylene is then forced into the 
tanks under pressure and is absorbed by the acetone. The 
safety of this means of storage lies in the degree of perfection to 
which the tanks are filled with the absorbent material. There 
must be no space anywhere in the tank where undissolved 
acetylene can exist. Its freedom from danger under such 
conditions has been thoroughly demonstrated in its use for 
railroad and automobile lamps. 

The use of acetylene as a fuel for cooking and for the various 
other purposes of domestic use is successfully accomplished in 
burners that give the blue flame desired for such purposes. 
Complete cooking ranges and various other heating and cooking 
devices are regularly sold by dealers in heating appliances, while 
water-heaters, hot-plates, chafing-dish heaters, etc., are as much 
a possibility as with any other of gaseous fuel and in as 
reasonably an inexpensive way. 

Coal gas, containing as it does sufficient carbon monoxide to 
render it poisonous, will cause death when inhaled for any length 
of time, but acetylene under the same conditions will have no 
deleterious effe(^t. 

Types of Acetylene Generators. — There are two general 
methods of generating acetylene for domestic illuminating and 



298 



MECHANICS OF THE HOUSEHOLD 



heating purposes: that of adding carbide to water, and that in 
which the water is mixed with carbide. The two types are 
illustrated in the diagrams shown in Figs. 209 and 210. The 
first method, that in which the carbide is dropped into water, is 
shown in Fig. 209. The tank A is the generator and B is the 
receiver or gas-holder. The tank A holds a considerable quantity 
of water and is provided with a container C for holding the supply 
of carbide. The tank A is connected with the gas-holders by a 
pipe which extends above the water line in the tank Bj where 
the gas is allowed to collect in the gas-holder G, A charge of 
carbide, sufficient to fill the holder with gas, is pushed into the 
tank A by raising the lever H, Immediately the water begins 
to combine with the carbide and the bubbles of gas pass up 



.iT^n 




A B 

Fig. 209. — Diagram of a carbide-to- 
water acetylene-gas generator. 




Fig. 210. — Diagram of a water-to- 
carbide acetylene-gas machine. 



through the water and are conducted into the tank B, The 
holder G is lifted by the gas and its weight furnishes the pressure 
necessary to force the gas into the pipes, which conduct it to the 
burners. If this machine were provided with the proper mechan- 
ism to feed into the generator a supply of carbide whenever the 
gas in the holder is exhausted, the machine would represent the 
modern ^^ carbide to water'' generator. 

The ^^ water to carbide'' generator is shown diagrammatically in 
Fig. 210. As in the other figure, A is the generator and B is the 
gas-holder. A supply of carbide S is placed in the generator 
and water from a tank C is allowed to drip or spray onto the 
carbide. The gas collects in the gas-holder as before. This 
apparatus represents in principle the parts of a machine for 
generating acetylene by this process. The actual machines are 



GASEOUS AND LIQUID FUELS 299 

arranged to perform the functions necessary to make the machines 
automatic in their action. 

Whatever the type of the machine, the object is to keep in the 
holders a sufficient amount of gas with which to supply the 
demand made on the plant. Machines representing each of the 
types described are to be obtained, but the greater number of those 
manufactured are of the ^^ carbide to water '^ form. 

In the formative period of acetylene generators many accidents 
of serious consequence resulted from imperfect mechanism. 
Imperfections have been gradually eliminated until the machines 
which have survived are efficient in action and mechanically 
free from dangerous eccentricities. 

The qualities demanded of a good generator are : There must 
be no possibility of an explosive mixture in any of the parts; it 
must insure a cool generation of gas; it must be well-constructed 
and simple to operate; it should create no pressure above a few 
ounces; it should be provided with an indicator to show how low 
the charge of carbide has become in order that it may be re- 
charged in due season, and it must use up the carbide completely. 

Because of the fact that the greater number of acetylene-gas 
machines of today are of the ^^ carbide to water '^ type, in the 
description to follow that type of machine is used. They are 
generally made in two parts, one part containing the generating 
apparatus and the other acting as gasometer (gas-holder), 
but some machines are made in which one cell contains both the 
generator and gasometer. 

In Fig. 211 is shown a two-part, gravity-fed machine, in which 
all of the internal working parts are exposed to view. The 
tank (a), as in the diagram, is the generator and the tank (6) 
contains the gasometer marked G. Each tank possesses a 
number of apphances which are necessary to make the machine 
automatic in its action. The part C of the generator contains 
the supply of carbide, broken into small pieces, a portion of 
which is dropped into the water whenever additional gas is 
required. The feed mechanism F is controlled by the gasometer 
bell Gy which is buoyed up by the gas it contains. When the 
supply of gas becomes low, the descending bell carries with it 
the end of the lever F, which is attached to the feed valve; 
this motion raises the feed valve and allows some of the carbide 



300 



MECHANICS OF THE HOUSEHOLD 



to fall into the water. The gas that is immediately generated 
passes into the gasometer through the pipe P, and as the bell is 
raised by the accumulating gas the valve V is closed. 

The gas as it enters the gasometer passes through a hollow 
device W, that looks like an inverted T, the lower edge of which is 
tooth-shaped and extends below the surface of the water. The 
gas, in passing this irregular surface, is broken up and comes 
through the water in little bubbles, in order that it may be washed 
clean of dust. This device also prevents the return of the gas 
to the generator tank during the process of charging. 




(a) W 

Fig. 211. — Sectional view of the Colt acetylene-gas machine. 



The gas escapes from the bell through the pipe S to the filter D, 
where any dust that may have escaped the washing process is 
removed by a felt filter. It finally leaves the machine by the 
pipe L, at which point it enters the system through which it is 
conveyed to the different lighting fixtures. 

It will be noticed that the tank (6) is divided into two compart- 
ments, the upper portion containing the water in which the gas- 
ometer floats. The lower compartment is also partly filled 
with water which acts as a safety valve to prevent any escape of 



GASEOUS AND LIQUID FUELS 



301 



gas into the room in which the generator is located. The lower 
end of the pipes P and S are immersed in the water at the bottom 
chamber of the tank, from which the gas could escape in case too 
much is generated and finally exit through the vent pipe U to 
the outside air. 

The float A in the tank (a) is a safety device that prevents the 
introduction of carbide unless the tank contains a full supply of 
water. The float is a hollow metal cylinder connected by a rod 
to a hinged cup under the bottom opening of the carbide holder. 
When the water is withdrawn from the generator, the float falls 
and the cup shuts off the carbide outlet. 




mm^mMmmmmMm^ 



Fig. 212. — Sectional view of a house equipped with acetylene lights and domestic 

heating apparatus. 

The accumulation of lime, from the disintegrated carbide, 
requires occasional removal from the tank (a).; the valve K is 
provided for this purpose. The lever S is used to stir up the lime 
which is deposited on the bottom of the tank, that it may be 
carried out with the discharged water. 

Machines of this kind that are safeguarded against leakage of 
gas or the possibility of accumulated pressure are practically free 
from danger in the use of acetylene. The accidental leakage of 
gas from defective pipes and fixtures prochice only the element of 
risk that is assumed with the use of any other form of gas for 
illuminating purposes. 



302 



MECHANICS OF THE HOUSEHOLD 



Acetylene is distributed through the house in pipes in the 
same manner as for ordinary illuminating gas. The sizes of the 
pipes to suit the varying conditions of use are regulated by rules 
provided by the National Board of Fire Underwriters. These 
rules state definitely the sizes of pipes required for machines of 
different capacities. Rules of this kind and others that specify 
all matters relating to the use of acetylene may be obtained 
from any fire insurance agent. 

The general plan of piping is shown in Fig. 212. The gen- 
erator G is in this case a ^^ water to carbide'' machine and is 
shown connected to the kitchen range, as well as the pipe system 
which may be traced to the lamps in the different rooms, to the 
porch lights and to the boulevard lamp in front of the building. 






Fig. 213.— Acety- Fig. 214.— Elec- Fig. 215.— Electric ig- 
lene gas burner. trie igniter for acety- niter for acetylene gas 
lene gas burners. burners. 

The type of burner used in acetylene lamps is shown in Fig. 
213. The gas issues from two openings to form the jet as it 
appears in the engraving. These burners are made in sizes to 
consume 34, 3-^, ^^,and 1 foot per hour depending on the amount of 
light demanded. 

Gas Lighters. — The acetylene gas jets are lighted ordinarily with 
a match or taper but electric igniters are often used for that pur- 
pose. Electric lighters for acetylene lamps are practically the 
same as those used with ordinary gas lamps but they must be 
adapted to the type of burner on which they are used. Electric 
igniters that are intended to be used with lamps placed in inacces- 
sible places are different in construction from those within reach. 
In Figs. 214 and 215 are illustrated two forms of igniters that 
are intended to be used on bracket or pendent lamps. They 



GASEOUS AND LIQUID FUELS 



303 



w 





differ in mechanical construction to suit two different conditions. 
Fig. 214 is an igniter in which is also included the gas-cock. The 
gas is lighted by pulling a cord or chain attached to the lever L. 
The movement of this lever turns on the gas and at the same 
time brings the piece C in contact with the wire A to complete 
an electric circuit. As the contact between these two pieces is 
broken, a spark is formed that ignites the gas escaping from the 
burner at B. On releasing the lever a spring returns the piece C 
to its original position. The light is extinguished by a second 
pull of the lever. 

Fig. 215 illustrates a style of igniter which may be attached 
to an ordinary gas-cock. It is attached to the stem of the burner 
by a clamp D, The gas is turned 
on by the usual gas-cock and by pull- 
ing the chain at the left the jet is 
lighted. In pulling the chain the arm 
A is raised and carries with it the 
arm B. When the arms A and B 
touch, an electric circuit is formed 
with a battery and spark coil. When 
the desired position of the arms is 
reached, the points separate to form 
an electric flash which lights the gas. 

Fig. 216 illustrates in A the method 
of installing electric igniters like those 
described. A battery B and a spark 
coil aS are joined in circuit as shown. The gas pipe acts as one 
of the wires of the circuit. A battery of four dry cells is com- 
monly used for the purpose. The spark coil is a simple coil of 
wire wound on a heavy iron core, which serves to intensify the 
spark when the circuit is broken. In using the igniter, it is 
only necessary to see that the cells are joined in series with the 
coil and attached to the insulated part of the igniter. As already 
explained the action of the igniter is to close the circuit and im- 
mediately break the contact at a point where the spark will ig- 
nite the gas. On being released the igniter returns to its original 
position. 

In the fixture shown at C is an igniter such as is used in places 
that cannot be conveniently reached. To light the jet, the circuit 



MMM^ 



Q ;|; Pipe 



D 



B 

Fig. 216. — Diagram of elec- 
tric igniters attached to gas 
burners. 



304 MECHANICS OF THE HOUSEHOLD 

is completed by turning the switch at W. As soon as the gas is 
hghted the switch is again turned to break the igniter-circuit. 
In this device the current passes through a magnet coil in the 
igniter which acts to open and close the circuit with the same effect 
as in the others. 

Acetylene Stoves. — Stoves in which acetylene is used as a fuel 
are quite similar in construction to those which burn coal gas. 
The principle of operation is that of mixing the acetylene with air 
in proper proportion so as to produce complete combustion 
when burned. 



CHAPTER XIII 
ELECTRICITY 

The adaptability of electricity to household use for lighting, 
heating and the generation of power has brought into use a host 
of mechanical devices that have found a permanent place in 
every community where electricity may be obtained at a reason- 
able rate, or where it can be generated to advantage in small 
plants. 

Because of its cleanliness and convenience, electricity is used 
in preference to other forms of lighting, even though its cost is 
relatively high. Electric power for household purposes is con- 
stantly finding new applications and will continue to increase in 
favor because its use as compared with hand power is remark- 
ably inexpensive. Small motors adapted to most of the ordi- 
nary household uses are made in convenient sizes and sold at 
prices that are conducive to their greater use. Human energy 
is far too precious to be expended in household drudgery 
where mechanical power can be used in its place and often to 
greater advantage. 

Electric heating devices compete favorably with many of the 
established forms of household heating appliances, the electric 
flat-iron being a notable example. In all applications where 
small amounts of heat are required for short periods of time, 
electricity is used at a cost that permits its use, in competition 
with other forms of heating. 

The remarkable advance that has taken place in elect ic 
transmission in the past few years tends to an enormous increase 
in its use. The constant increase in its use for lighting, heating 
and power purposes is due in a great measure to the development 
of efficient electric generating plants from which this energy may 
be obtained at the least cost. In those communities where 
20 305 



306 MECHANICS OF THE HOUSEHOLD 

hydro-electric generation is possible its field of application is 
almost without end. 

Incandescent Electric Lamps. — Anything made in the form of 
an illuminating device, in which the lighting element is rendered 
incandescent by electricity, may properly be called an in- 
candescent lamp, whether the medium is incandescent gas as in 
the Moore lamp, an incandescent vapor as the Cooper Hewitt 
mercury-vapor lamp, or the incandescent filament of carbon or 
metal such as is universally used for lighting. 

From the year 1879, when Mr. Edison announced the perfec- 
tion of the incandescent electric lamp, until 1903, when for a short 
period tantalum lamps were used, very little improvement had 
been made in the carbon-filament lamp. Immediately following 
the introduction of the tantalum lamp came the tungsten lamp, 
which because of its wonderfully increased capability for pro- 
ducing light has extended artificial illumination to a degree 
almost beyond comprehension. The influence of the tungsten 
lamp has induced a new era of illumination that has affected the 
entire civilized world. The development of the high-efficiency 
incandescent lamp has brought about a revolution in electric 
lighting. Its use is universal and its application is made in every 
form of electric illumination. 

Regardless of the immense number of tungsten lamps in use, 
the carbon-filament lamp is still employed in great numbers and 
will probably continue in 'use for a long time to come. In 
places where lamps are required for occasional use and for short 
intervals of time, the carbon filament still finds efficient use. 
In one form of manufacture the carbon filament is subjected to a 
metalizing process that materially increases its efficiency. 
This form, known commercially as the GEM lamp, fills an 
important place in electric lighting. 

Of the rare-metal filament lamps, those using tungsten and 
tantalum are in general use, but the tungsten lamps give results 
so much superior in point of economy in current consumed 
that the future filament lamps will beyond doubt be of that 
type unless some other material is found that will give better 
results. 

The filaments of the first tungsten lamps were very fragile 
and were so easily broken that their use was limited, but in a 



ELECTRICITY 307 

very short time methods were found for producing filaments 
capable of withstanding general usage and having an average 
life of 1000 hours of service. These lamps give an efficiency of 
1.1 to 1.25 watts per candlepower of light, as will be later more 
fully explained. This, as compared with the carbon-filament 
lamps which average 3.1 to 4.5 watts per candlepower, gives a 
remarkable advantage to the former. The tungsten lamp has a 
useful life that for cost of light is practically one-third that of the 
carbon-filament lamp. 

The metal tungsten, from which the lamp filament is made, 
was discovered in 1871. It is not found in the metallic state 
but occurs as tungstate of iron and manganese and as calcium 
tungstate. Up to 1906 it was known only in laboratories and 
on account of its rarity the price was very high. As greater 
bodies of ore were found and the process of extraction became' 
better known, the price soon dropped to a point permitting its 
use for lamp filaments in a commercial scale. 

Pure tungsten is hard enough to scratch glass. Its fusing 
point is higher than any other known metal; under ordinary con- 
ditions it is almost impossible to melt it and this property gives 
its value as an incandescent filament. One of the laws that affect 
the lighting properties of incandescent lamps is: ^Hhe higher the 
temperature of the glowing filament, the greater will be the 
amount of light furnished for a given amount of current con- 
sumed.'' The high melting point permits the tungsten filament 
to be used at a higher temperature than any other known mate- 
rial. Tungsten is not ductile, and in ordinary form cannot be 
drawn into wire. Because of this fact, the filaments of the 
first lamps were made by the ^^ paste'' process, which consisted 
of mixing the powdered metal with a binding material, in the 
form of gums, until the mass acquired a consistency in which it 
might be squirted through a minute orifice in a diamond dye. The 
resulting thread was dried, after which it was heated, and finally 
placed in an atmosphere of gases which attacked the binding ma- 
terial without affecting the metal. When heated by electric- 
ity in this condition, the particles of metal fused together to form 
a filament of tungsten. While the ^^ paste" filaments were never 
satisfactory in general use, their efficiency as a light-producing 



308 



MECHANICS OF THE HOUSEHOLD 



GJass Bulb- 



-Top Anchors 



agent inspired a greater diligence in the search for a more durable 
form. 

Although tungsten in ordinary condition is not at all ductile, 
methods were soon found for making tungsten wire and the 
wire-filament lamps are now those of general use. One process 
of producing the drawn wire is that of filling a molten mass of a 
ductile metal with powdered tungsten after which wire is drawn 
from the mixture in the usual way. The enclosing metal is then 
removed by chemical means or volatilized by heat. 

Of the difficulties encountered in the use of metal-filament 
lamps that of the low resistance offered by the wire was over- 
come by using filaments very 
small in cross-section and of as 
great length as could be con- 
veniently handled. The long 
tungsten filament requires a 
method of support very differ- 
ent from the carbon lamp. 
The characteristic form of 
tungsten lamps is shown in 
Fig. 217, in which the various 
parts of the lamp are named. 

The filament of an incandes- 
cent lamp is heated because of 
the current which passes 
through it. The electric pres- 
sure furnished by the voltage, forces current through the filament 
in as great an amount as the resistance will permit. A 16-candle- 
power carbon lamp attached to a 110-volt circuit requires practi- 
cally 3-^ ampere of current to render the filament incandescent; the 
filament resistance must, therefore, allow the passage of 3-^ ampere. 
With a given size of filament, its length must be such as will 
produce the desired resistance. A greater length of this filament 
would give more resistance and a correspondingly less amount 
of current would give a dim light because of its lower temperature. 
Likewise, a shorter filament would allow more current to pass 
and a brighter light would result. When the size and length of 
filament is once found that will permit the right amount of current 
to pass, if the voltage is kept constant, the filaments will always 




Air -Tight- 
Seal 



Brass Screw 
Shell of Base 



-Glass Stem 



Glass Insulation 



Brass Cap Contact 

Fig. 217. — An Edison Mazda lamp 
and its parts. 



ELECTRICITY 309 

burn with the same brightness. This is in accordance with Ohm's 
law which as stated in a formula is 

E = RC 

that is Ej the electromotive force in volts, is always equal to the 
product of the resistance R, in ohms, and the current C, in 
amperes. 

In the incandescent lamp, if the electrotromotive force is 110 
volts and the current is }^ ampere, the resistance will be 220 ohms 
and as expressed by the law 

110 = 220 X 0.5 

From this it is seen that any change in the voltage will produce 
a corresponding change in the current to keep an equality in the 
equation. If the voltage increases, the current also increases 
and the lamp burns brighter. Should the voltage decrease the 
current will decrease and the lamp will burn dim. This dim- 
ming effect is noticeable in any lighting system whenever there 
occurs a change in voltage. 

The quantity of electricity used up in such a lamp is expressed 
in watts, which is the product of the volts and amperes of the 
circuit. In the lamp described, the product of the voltage (110) 
by the amount of passing current (3-^ ampere) is 55 watts. With 
the above conditions the 16 candlepower of light will require 3.43 
watts in the production of each candlepower. The best per- 
formance of carbon-filament lamps give a candlepower for each 
3.1 watts of energy. 

The filament of the tungsten lamp must offer a resistance 
sufficient to prevent only enough current to pass as will raise 
its temperature to a point giving the greatest permissible amount 
of light, and yet not destroy the wire. The high fusing point 
and the low specific heat of tungsten permits the filament to be 
heated to a higher temperature than the carbon filament and with 
a less amount of electric energy. These are the properties that 
give to the tungsten lamp its value over the carbon lamp. 

The exact advantage of the tungsten lamp has been investi- 
gated with great care and its behavior under general working con- 
ditions is definitely known. In light-giving properties where the 
carbon-filament lamp requires 3.1 watts to produce a candlepower 



310 MECHANICS OF THE HOUSEHOLD 

of light, in the tungsten filament only 1.1 watts are necessary 
to cause the same effect. The tungsten lamp therefore gives 
almost three times as much light as the carbon lamp for the same 
energy expended. The manufacturers aim to make lamps that 
give the greatest efficiency for a definite number of hours of serv- 
ice. It has been agreed that 1000 working hours shall be the 
life of the lamps and in that period the filament should give its 
greatest amount of light for the energy consumed. 

The Mazda Lamp. — The trade name for the lamp giving the 
greatest efficiency is Mazda. The term is taken as a symbol 
of efficiency in electric incandescent lighting. At present the 
Mazda is the tungsten-filament lamp, but should there be found 
some other more efficient means of lighting, which can take its 
place to greater advantage, that will become the Mazda lamp. 

Candlepower. — The incandescent lamps are usually rated m 
light-giving properties by their value in horizontal candlepower. 
This represents the mean value of the light of the lamp which 
comes from a horizontal plane passing through the center of 
illumination and perpendicular to the long axis of the lamp. 
Candlepower in this connection originally referred to the English 
standard candle which is made of spermaceti. The standard 
candle is 0.9 inch in diameter at the base, 0.8 inch in diameter at 
the top and 10 inches long. It burns 120 grains of spermaceti and 
wick per hour. This candle is not satisfactory as a standard 
because of the variable conditions that must surround its use. 
The American or International standard is equal to 1.11 Hefner 
candles. The Hefner candle (which is the standard in con- 
tinental Europe and South American countries) is produced by a 
lamp burning amylacetate. This lamp consists of a reservoir 
and wick of standard dimensions which gives a constant quan- 
tity of light. The light from this lamp has proven much more 
satisfactory as a means of measurement of light than the English 
standard and therefore its use has been very generally adopted. 

The light given out by an incandescent lamp is not the same 
in all directions. In making comparisons it is necessary to define 
the position from which the light of the lamps is taken. The 
horizontal candlepower affords a fairly exact means of com- 
paring lamps which have the same shape of filament, but for 
different kinds of lamps it does not give a true comparison. The 



ELECTRICITY 311 

spherical candlepower is used to compare lamps of different con- 
struction as this gives the mean value at all points of a sphere 
surrounding the lamp. The candlepower is measured at various 
positions about the lamp with the use of a photometer, and the 
mean of these values is taken as the mean spherical candlepower. 

At their best, carbon-filament lamps require in electricity 
3.1 w.p.c. (watts per candlepower). As the lamp grows old the 
number of watts per candle power increases, until in very old 
lamps the amount of electricity used to produce a given amount 
of light may become excessively large. According to a bulletin 
issued by the Illinois Engineering Experiment Station on the 
efficiency of carbon-filament incandescent lamps, the amount of 
electrical energy per candlepower varied from 3.1 w.p.c, when 
new, to 4.2 w.p.c, after burning 800 hours. 

A common practice in the use of carbon-filament lamps is to 
consider that the period of useful life ends at a point where the 
amount of electricity, per candlepower, reaches 20 per cent, in 
excess of the original amount. This point (sometimes termed 
the smashing point) would be reached after 800 working hours, 
according to the Illinois Station, and at about 1000 hours as 
stated by the bulletins of the General Electric Co. If a carbon- 
filament lamp burns for an average period of 3 hours a day for a 
year, it ought to be replaced. 

The Edison screw base as shown in Fig. 217 is now generally 
used in all makes of incandescent lamps for attaching the lamp 
to the socket. When screwed into place this base forms in the 
socket the connections with the supply wires, to produce a cir- 
cuit through the lamp. One end of the filament is attached to the 
brass cap contact, the opposite end connects with the brass screw 
shell of the base. When the current is turned on, the contact 
made in the switch is such as to form a complete circuit between 
the supply wires; the voltage sending a constant current through 
the lamp produces a steady incandescence of the filament. 

In Fig. 218 is shown a carbon-filament lamp attached to an 
ordinary socket. The lamp base and socket are shown in section 
to expose all of the parts that comprise the mechanism. The in- 
sulated wires of the lamp cord enter tlie top of the socket and the 
ends attach to the binding screws A and B, which are insulated 
from each other and form the brass shell which encases the socket. 



312 



MECHANICS OF THE HOUSEHOLD 



The lamp base is shown screwed into the socket, the brass cap 
contact F making connection at G] the screw shell joins the socket 
at Z). To the key S is attached a brass rod R, on which is fastened 
E, the contact-maker. The rod R passes through a sup- 
portary frame which is secured to the lamp socket at G. As 
shown in the figures the piece E makes contact with a brass 
spring attached to A^ and this completes a circuit through the 
filament. The brass cap contact of the lamp base makes con- 
nection at one end of the filament H^ the 
other end of the filament K is attached to 
the brass screw shell of the base, which in 
turn connects with the screw shell of the 
socket and^this shell is connected with the 
piece containing the binding screw B by the 
rod C to complete the circuit. When the 
key >S turns, the contact above E is broken 
and the lamp ceases to burn. 

Fig. 118 shows the use of an adapter 
that is sometimes encountered in old elec- 
tric fixtures, the use of which requires ex- 
planation. Mention has already been made 
of the various forms of lamp sockets in use 
before the Edison base became a standard. 
In order to use an Edison lamp in a socket 
intended for another form of base an adap- 
ter must be employed to suit the new base 
to the old socket. In the figure the piece 
Pi, is the adapter. This is intended to 
adapt the standard lamp base to a socket 
that was formerly in use on the Thompson-Houston system of 
electric lighting. The adapter is joined to the old socket by the 
screw at G and the circuit formed as already described. 

Lamp Labels. — For many years all incandescent lamps were 
rated in candlepower and were made in sizes 8, 16, 32, etc., candle- 
power. On the label was printed the voltage at which the lamp 
was intended to operate, and also the candlepower it was sup- 
posed to develop. Thus 110 v., 16 cp. indicated that when used 
on 110-volt circuit, the lamp would give 16 candlepower of light. 
This label in no way indicated the amount of energy expended. 




Fig, 218. — Section of a 
lamp base and socket. 



ELECTRICITY % 313 

With the development of the more efficient filaments came a 
tendency to label lamps in the amount of energy consumed. This 
has resulted in all lamps being labeled to show the voltage of the 
circuit suited to the lamp, and the watts of electricity consumed 
when working at that voltage. At present a lamp label may be 
marked 110 v., 40 w., which indicates that it is intended to 
develop its best performance at 110 volts and will consume 40 
watts at that voltage. 

Commercial lamps are now manufactured in sizes of 10, 15, 
25, 40, 60, 75, and 100 watts capacity for ordinary use. Of these 
the 40-watt lamp probably fulfills the greatest number of con- 
ditions and is most commonly used. Besides these there are 
the high-efficiency lamps of the gas-filled variety that are made 
in larger sizes and the miniature lamps in great variety. All 
are labeled to show the volts and the watts consumed. 

Illumination. — The development of high-efficiency lamps has 
caused a radical change in the methods of illumination. With 
cheaper light came the desire to more nearly approximate the 
effect of daylight in illumination. This has brought into use 
indirect illumination, in which the light from the lamp is diffused 
by reflection from the ceiling and walls of the room. Illuminating 
engineering is now a business that has to do with placing of lamps 
to the greatest advantage in lighting any desired space. In 
large and complicated schemes of lighting professional services 
are necessary, but in household lighting the required number of 
lamps for the various apartments are almost self-evident. The 
lighting of large rooms, however, requires thoughtful consider- 
ation and in many cases the only definite solution of the prob- 
lem is that of calculation. 

The Foot-candle. — The amount of illumination produced over 
a given area depends not only on the number of lamps and their 
candlepower, but upon their distribution and the color of the 
walls and furnishings. In the calculation of problems in illumina- 
tion, units of measure are necessary to express the amount of 
light that will be furnished at any point from its source. The 
units adopted for such purposes ai'o tlie foot-candle and the 
lumen. 

The Lumen. — A light giving 1 candlepower, placed in the 
center of a sphere of 1 foot radius illuminates a sphere, the area 



314 .MECHANICS OF THE HOUSEHOLD 

of which is 4 X 3.1416 or 12.57 square feet. The intensity of 
Hght on each square foot is denoted as a candle-foot. The 
candle-foot is the standard of illumination on any surface. The 
quantity of light used in illuminating each square foot of the 
sphere is called a lumen. A light of 1 candlepower will there- 
fore produce an intensity of 1 candle-foot over 12.57 square 
feet and give 12.57 lumens. Therefore, if all of the light is 
effective on a plane to be illuminated, a lamp rated at 400 lumens 
would light an area of 400 square feet to an average intensity of 
1 candle-foot. 

' To find the number of lamps required for lighting any space, 
the area in square feet is multiplied by the required intensity 
in foot-candles, to obtain the total necessary lumens, and the 
amount thus obtained is divided by the effective lumens per 
lamp. 

The bulletins of the Columbia Incandescent Lamp Works 
gives the following method of calculating the number of lamps 
required to light a given space: 

/S X 7 

Number of lamps = ^r;^^ — t- \ \ 

^ li/ffective lumens per lamp 

S (square feet) X I (required illumination in foot- 
candles) = total lumens. 

The total lumens divided by the number of effective lumens 
per lamp gives the number of lamps required. In using the 
formula the effective lumens per lamp is taken from the follow- 
ing table: 

Watts per lamp 25 40 60 

Effective lumens per lamp 95 160 250 
Lumens per watt 3.8 4.0 4.2 

The size of the units is a matter of choice since six 400-lumen 
units are equal to four 600-lumen units in illuminating power, 
etc. In deciding upon the proper size of lamps to use, consider- 
ation must be taken of the outlets if the building is already wired. 
In general the fewest units consistent with good distribution will 
be the most economical. The table shows the lumens effective 
for ordinary lighting with Mazda lamps and clear high-efficiency 
reflectors with dark walls and ceiling. Where both ceiling and 
walls are very light these figures may be increased by 25 per cent. 



160 


150 


250 


420 


630 


1090 


4.2 


4.2 


4.3 



ELECTRICITY 



315 



To illustrate the use of the table, take an average room 16 by 
24 to be lighted with Mazda lamps to an intensity of 3.5 foot- 
candles. If clear Holoplane reflectors are used, the values for 
lumens effective on the plane may be increased 10 per cent, 
due to reflection from fairly light walls. The lamps in this case 
are to be of the 40-watt type which in the table are rated at 160 
lumens. To this amount 10 per cent, is added on account of the 
reflectors and walls. This data applied to the formula gives: 

s = 16 by 24 feet 

/ = 3.5 

Lumens per lamp = 160 

(16 X 24) X 3.5 



= eight 40-watt lamps. 




ENCLOSING UNIT 



SEMI- INDIRECT 
UNIT 

Fig. 219. 



COLOR MATCHING UNIT 



Reflectors. — The character and form of reflectors have much 
to do with the effective distribution of the light produced by 
the lamp. The most efficient form of reflectors are made of 
glass and designed to project the light in the desired direction. 
The illustration in Fig. 219, marked open reflector, shows the 
characteristic features of reflectors designed for special purposes. 
They are made of prismatic glass fashioned into such form as 
will produce the desired effect and at the same time transmit 



316 MECHANICS OF THE HOUSEHOLD 

and diffuse a part of the light to all parts of the space to be 
lighted. The greater portion of the light is sent in the direction 
in which the highest illumination is desired. The reflectors 
are made to concentrate the light on a small space or to spread 
it over a large area as is desired. They are, therefore, designated 
as intensive or extensive reflectors and made in a variety of forms. 

Choice of Reflector. — Where the light from a single lamp must 
spread over a relatively great area, it is advisable to use an 
extensive form of reflector. This reflector is applicable to general 
residence lighting, also uniform lighting of large areas where 
low ceilings or widely spaced outlets demand a wide distribution 
of light. Where the area to be lighted by one lamp is smaller, 
the intensive reflector is used. Such cases include brilliant 
local illumination, as for reading tables, single-unit lighting or 
rooms with high ceilings as pantries or halls. 

Where an intense light on a small area directly below the 
lamp is desired, sl focusing reflector is used. The diameter of the 
circle thus intensely lighted is about one-half the height of the 
lamp above the plane considered. Focusing reflectors are used 
in vestibules or rooms of unusually high ceilings. 

Type Height above plane to be lighted 

Extensive ^i J^ 

Intensive % J^ 

Focusing /^ -D 

D = distance between sides of room to be illuminated. 

The various other fixtures of Fig. 219 that are designated 
as reflectors are in some cases only a means of diffusion of light. 
In the use of the high-eflSiciency gas-filled lamps the light is too 
bright to be used directly for ordinary illumination. When these 
lamps are placed in opal screens of the indirect or the semi- 
indirect form the light produced for general illumination is 
very satisfactory. Considerable light is lost in passing through 
the translucent glass but this is compensated by the use of the 
high-efficiency lamps and the general satisfaction of light dis- 
tribution. 

Lamp Transformers. — ^Lamps of the Mazda type, constructed 
to work at the usual commercial voltages, are made in low-power 
forms to consume as little as 10 watts; but owing to the difficulty 
of arranging a suitable filament for the smaller sizes of lamps, 



ELECTRICITY 



317 



less voltage is required to insure successful operation. The 
lamps for this purpose are of the type used in connection with 
batteries and require 1 or more volts to produce the desired 
illumination. When these little lamps are used on a commercial 
circuit; the reduction of the voltage is accomplished by small 
transformers, located in the lamp socket. The operating prin- 
ciple and further use of the transformers will be explained later 
under doorbell transformers. The lamp transformer, although 
miniature in design, is constructed as any other of its kind but 
designed to reduce the usual voltage of the circuit to 6 volts of 
pressure. The socket is that intended for the use of the Mazda 
automobile lamp giving 2 candlepower. This lamp used with 
electricity at the average rate per kilowatt can be burned for 
10 hours at less than half a cent. In bedrooms, sickrooms and 




^ D 

Fig. 220. — Miniature lamp transformer complete and the parts of which it is 

composed. 

other places where a small amount of light is necessary but where 
a considerable quantity is objectionable, the miniature lamp 
transformer serves an admirable purpose in adapting the 
voltage of the commercial alternating circuit to that required 
for lamps of small illuminating power. Such a transformer is 
shown in Fig. 220. 

The figure shows in A the assembled attachment with the lamp 
bulb in place. The part B, the transformer, changes the line 
voltage to that of a battery lamp. A line voltage of 110 may be 
transformed to suit a 6-volt miniature lamp. The parts C and 
D compose the screw base and the cover, in which is fitted the 
transformer B. 

Units of Electrical Measurement. — The general application 
of electricity has brought into common use the terms necessary in 
its measurement and units of quantity by which it is sold. The 
volt, ampere and ohm are terms that are used to express the con- 



318 MECHANICS OF THE HOUSEHOLD 

ditions of the electric circuit; the watt and the kilowatt are units 
that are employed in measuring its quantity in commercial usage. 
The use of these units in actual problems is the most satis- 
factory method of appreciating their application. 

As already explained the volt is the unit of electric pressure 
which causes current to be sent through any circuit. The elec- 
tric circuits of houses are intended to be under constant voltage — 
commonly 110 or 220 — but the voltage may be any amount for 
which the generating system is designed. Independent lighting 
systems such as are used in house-lighting plants — to be de- 
scribed later — commonly employ 32 volts of electric pressure. 

Opposed to the effect of the volts of electromotive force is 
the resistance of the circuit, which is measured in ohms. Re- 
sistance has been called electric friction; it expresses itself as 
heat and tends to diminish the flow of current. Every circuit 
offers resistance depending on the length, the kind and the size 
of wire used. Since the wires of commercial lighting systems 
are made of copper, it can be said that the resistance of the 
circuit increases as the size of the conducting wire decreases. 
. In large wires the resistance is small but as the size of the wire 
is reduced the resistance is increased. A long attachment 
cord of a flat-iron, may offer sufficient resistance to prevent 
the iron from heating properly. 

The ampere is the unit which measures the amount of current. 
The amperes of current determine the rate at which the electric- 
ity is being used in any circuit. The wires of a house must be 
of a size sufficient to carry the necessary current without heat- 
ing. Any house wire which becomes noticeably warm is too small 
for the current it carries and should be replaced by one that is 
larger. 

The watt is the unit of electric quantity. The quantity of 
electricity being used in any circuit is the product of the volts 
of pressure and amperes of current flowing through the wires. 
The amount of current — in amperes — sent through the circuit is 
the direct result of the volts of pressure; the quantity of electricity 
is therefore the product of these two factors. A 25- watt lamp on 
a circuit of 110 volts uses 0.227 ampere of current. 

25 watts = 110 volts X 0.227 amperes. 



ELECTRICITY 319 

Ten such lamps use 

10 X 0.227 amperes = 2.27 amperes.. 

The product of 110 volts and 2.27 amperes is 250 watts. 

In order to express quantity of energy, it is necessary to state 
the length of time the energy is to act and originally the watt 
represented the energy of a volt-ampere for one second. For 
commercial purposes this quantity is too small for convenient use 
and the hour of time was taken instead. The watt of commercial 
measurement is the watt-hour and in the purchase of electricity 
the watt is always understood as that quantity. 

Even as a watt-hour the measure is so small as to require a 
large number to express ordinary amounts and a still larger unit 
of 1000 watt-hours or the kilowatt-hour was adopted and has be- 
come the accepted unit of commercial electric measurement. Just 
as a dollar in money conveniently represents 1000 mills so does a 
kilowatt of electricity represent a convenient quantity. 

In the purchase of electricity, the consumer pays a definite 
amount, say 10 cents per kilowatt. This represents an exact 
quantity of energy, that may be expended in light, in heat, or in 
the generation of power, all of which may be expressed as definite 
quantities. 

As light, it indicates in the electric lamp the number of candle- 
power-hours that may be obtained for 10 cents. At this rate 
a single watt costs 0.01 cent an hour. A 25-watt electric lamp will 
therefore cost 0.25 (3^) cent for each hour of use; a 60-watt 
lamp costs 0.6 cent per hour; the ten 25-watt lamp mentioned 
above using 250 watts costs 2.5 cents per hour. 

As heat, it is expressed in English-speaking countries as Brit- 
ish thermal units, 1 kilowatt-hour representing 3412 B.t.u. per 
hour. One cent's worth of electricity at the rate given yields 
341.2 B.t.u. of heat. 

As power, it represents an exact amount of work. So expressed, 

a watt represents YJa horsepower; therefore a kilowatt is repre- 
sented in power as YaK "^1*^ horsepower. Since the kilowatt 

purchased for 10 cents is a kilowatt-hour, the equivalent horse- 
power is for the same length of time. At the assumed rate, 10 
cents buys 1.3 horsepower for one hour. When used as work 



320 



MECHANICS OF THE HOUSEHOLD 



it represents 2,544,000 foot-pounds or 255,400 foot-pounds of 
work for 1 cent. This work when expended in a motor, to 
do the family washing or perform any other household drudgery, 
represents the greatest value to be derived from its use. A 3^^- 
horsepower motor is amply large to operate a family washing 
machine. Even though the motor is only 50 per cent, efficient 
its cost of operation is less than 7 cents per hour. 

Miniature Lamps. — Miniature electric lamps include all that 
are not used for general illuminating purposes. The term applies 
more particularly to the form of the base than to the voltage 
or candlepower of the filament. There are three general classes 
of these lamps : candelabra and decorative, that operate on light- 
ing circuits of 100 to 130 volts and are usually intended for deco- 



d 







Candelabra screw Minature screw Double-contact bayo- Single-contact bayo- 
base base net candelabra base net candelabra base 

Fig. 221. — Miniature lamp bases. 

rative purposes; general battery lamps used for flash lights; and 
lamps for automobiles and electric-vehicle service. 

The term miniature lamp applies more particularly to the 
base than to the voltage or candlepower. The style of base is 
characteristic of the service for which the lamp is designed rather 
than the size or number of watts consumed. There are two 
general styles of bases: the screw type of the Edison construc- 
tion of which there are two sizes; and the bayonet type of which 
there are two styles of construction. 

Bases for miniature lamps are made in form to suit the condi- 
tions of their use. The styles at present are shown in Fig. 221. 
Of these the screw bases at the left are those attached to small 
flash-lamp bulbs and others of the smaller sizes of lamps. The 
two at the right of the figure are the bayonet style used under 
conditions not suited to the screw contact. In the case of auto- 
mobile lamps and in places where vibration will cause loss of 
contact the bayonet base is generally in use. The lamp is held 
in place by the projecting lugs that engage with openings in the 



ELECTRICITY 



321 



socket and kept in place by the pressure of a spring. The 
contact with the lamp filament is made by two terminals that 
make connection directly with the terminals of the lamp filament. 
The single contact base is kept in place similarly to that of the 
other but makes a single contact at the end of the socket while 
the other but makes a single contact at the end of the socket 
while the circuit is completed through the pressure exerted be- 
tween the projecting lugs and the socket. 

Effect of Voltage Variations. — Voltage variation may be tem- 
porary, due to changing load in the circuit, or in constantly 
overloaded circuits the voltage may be 
constantly below normal. The change 
in electric pressure affects in a consider- 
able degree the amount of light given 
by the lamp. As an example, a 5 per 
cent*, drop from the normal voltage will 
cause a decrease of 31 per cent, in the 
amount of light given. This means 
that if a lamp is working on a circuit 
of 110 volts and the voltage from any 
cause were to drop to 1043-^ volts, the 
light would decrease 6.8, almost 7 
candlepower. Drop in voltage may also 
be due to the resistance of wires that 
are too small for the service. Lamps 
attached to such a circuit will constantly 
burn dim. 

Turn-down Electric Lamps. — The 
ordinary incandescent lamp lacks the 
flexibility of gas and oil lamp, in that 
the amount of light cannot be varied 
at will. This feature is attained in the 
electric turn-down lamp either by resistance added to the lamp 
circuit or by the use of two separate filaments in a single globe; 
one of ordinary lamp size and the other of such size that it con- 
sumes only a fraction as much energy as the normal lamp. 

Turn-down lamps of the latter form are made in several styles, 
the chief points of difference being in the method of changing 
the contact from the high- to the low-power filament. In Fig. 222 

21 




Fig. 222. — Sectional view 
of a "turn-down" lamp 
socket. 



322 MECHANICS OF THE HOUSEHOLD 

a sectional view shows the ^^ pull-string^' form of lamp in which 
the parts are exposed. The long filament H and the smaller one 
L represent two individual lamps of different lighting power. 
The change in light is made from one to the other by pulling the 
string which is attached to a switch in the socket and which 
changes the contact to send the current through the filament 
giving the desired amount of light. The figure shows a carbon- 
filament lamp, but tungsten lamps are made to accomplish the 
same purpose. The difficulty of manufacturing a 1-candlepower 
tungsten lamp for direct operation on a 110-volt circuit requires 
the filaments to work in series. The figure is arranged on the 
same plan as for a tungsten lamp. 

The lamp base when screwed into the socket makes contact 
with the two service wires of the circuit at A and at £', Which 
are part of the screw base. To light the lamp the current is 
switched on as in any lamp. The current enters at A and passes 
down the connecting piece to the contact B, The piece B is 
moved by the cord to light either the large or the small filament. 
In the position shown the current enters the small filament at C 
and in order to complete the circuit to E must traverse both the 
large and the small filament. The resistance of the small fila- 
ment is such that the passing current raises it to a temperature 
of incandescence but the large filament does not heat sufficiently 
to give an appreciable amount of light. When the cord is pulled 
to light the large filament, the contact is made at D and the 
current passes directly through the large filament to complete 
the circuit at E, 

Turn-down lamps are especially adapted to the home. Their 
use in a child's bedroom or sick chamber is a great convenience. 
The lamps are often constructed with a long-distance cord extend- 
ing from a fixture to the bedside. By this means a dim or bright 
light is given as desired, with the least inconvenience. Turn- 
down lamps are made in a variety of sizes. The large filaments 
are arranged to give 8, 16, and 32 candlepower. With the 8- 
candlepower lamp the small filament gives ^^ candlepower and 
with the 16- and 32-candlepower the small filament gives 1 
candlepower. 

With the lamps described, the variation in amount of light 
is attained by changing the contacts, to bring into action fila- 



ELECTRICITY 



323 



ments of different resistances. They admit of only two changes, 
either the lamp burns at full capacity or at the least light the 
lamp will give. The heat liberated by the large filament, when 
the small light is in use, takes place inside the lamp globe. 

The Dim-a-lite. — In another form of turn-down lamp the 
change in amount of light is produced by external resistance in 
the circuit. The resistance is furnished by a coil of wire which is 
enclosed in a special lamp socket. It possesses the advantage 
as a turn-down lamp in a number of changes of light. The added 
resistance in a socket decreases the flow of current and, therefore, 
the filament gives less light. The resistance wire is divided into 
a number of sections and contact with the ter- 
minals of these sections decreases the light with 
each addition of resistance. The heat generated 
in the resistance coils is dissipated by the brass 
covering of the socket. 

An illustration of a turn-down lamp using a 
separate resistance is that of Fig. 223, known 
commercially as the Dim-a-lite, which is an ex- 
cellent example. The Dim-a-lite attachment is 
a lamp socket in which is enclosed a miniature 
rheostat or resistance unit. The lamp, when 
placed on the Dim-a-lite, makes electrical con- 
tact as in an ordinary socket but with the 
difference that in series with the lamp filament 
is the rheostat, by means of which additional re- 
sistance may be added to change the current flow- 
ing in the lamp. The rheostat is so arranged that contact may be 
made at four different points in the resistance coil, through which 
the electricity may be varied from 100 to 20 per cent, of the 
normal quantity. The resistance in any case permits current to 
pass through the filament in amounts of 70, 30 and 20 per cent, of 
the normal amount. In use, the variation is made by pulling one 
string to add resistance and thus dim the light; or by pulling the 
other string, the resistance is decreased and more electricity 
passes through the filament to produce a brighter light. The 
quantity of light given out by the filament does not vary in the 
ratio of the added resistance but a variable light is obtained at 
the expense of a small amount of electricity which is changed 




Fig. 223.— 
The resistance 
type of ** turn- 
down" lamp. 



324 



MECHANICS OF THE HOUSEHOLD 




into heat. When the Hght is burning at its dimmest only 20 per 
cent, of the normal current is used. Under this condition the 
light given out by filament does not express the high efficiency 
attained when the lamp is burning at its full power but it does 
give a convenient form of light regulation with the 
minimum waste of energy. 

Gas-filled Lamps. — Until 1913 the filaments of 
all Mazda lamps operated in a vacuum. The vacuum 
serving the purpose of preventing oxidation and at 
the same time it reduced the energy loss to the 
least amount. It was found, however, under some 
conditions of construction that lamps filled with 
inert gas gave a higher efficiency and more satisfac- 
— 4 0- watt *^^y service than those of the vacuum type. In this 
Mazda B construction, the filament is operated at a tempera- 
sca^V ^^^^ much higher than that of the vacuum lamp 

and as a consequence gives light at a less cost per 
candlepower. Mazda vacuum lamps are now designated by the 
General Electric Co. as Mazda B lamps. Fig. 224, and those of 
the gas-filled variety, Fig. 225, are designated as Mazda C lamps. 
The filaments of the gas-filled lamps are intensely brilliant and 
where they come within the line of vision should be screened from 
the eyes. The high efficiency of these lamps 
permit the use of opal shades to produce a de- 
sired illumination at a rate of cost that com- 
pares favorably with the unscreened light of the 
vacuum lamps. ' 

Daylight Lamps. — The color of the light from 
an incandescent electric lamp depends on the 
temperature of the filament. In the case of the 
gas-filled Mazda lamp the high filament tem- 
perature produces a light that differs markedly 
from the vacuum lamps in that it contains a 
greater amount of blue and green rays. It is 
therefore possible to produce light that is the 
same as average daylight. Gas-filled lamps with 
globes colored to produce light of noonday quality are produced 
at an expenditure of 1.2 watts per candlepower. 

In the matching of colors, it should be kept in mind that the 




Fig. 225.— 750- 
watt Mazda C 
lamp (Ji scale). 



ELECTRICITY 325 

tint of any color is influenced by the kind of light by which it is 
viewed. Colors matched by ordinary incandescent light con- 
taining a large percentaga of red rays cannot produce the same 
effect when the same articles are seen in light of different 
quality. The daylight lamps are therefore intended to be used 
under conditions that require daylight quality. 

Miniature Tungsten Lamps. — The wonderful light-giving prop- 
erties of tungsten has made possible the use of miniature in- 
candescent lamps for an almost infinite variety of usages. The 
miniature lamps are similar in action to other incandescent elec- 
tric lamps except that they are operated on voltages lower than 
is used on commercial circuits. When used on commercial 
circuits, incandescent tungsten lamps of less than 10 watts 
capacity require filaments that are too delicate to withstand the 
conditions of ordinary use. The properties of tungsten are such 
that the passage of only a small amount of current is required 
to render the filament incandescent. In the case of a 110- volt 
circuit, a 10- watt lamp requires only 0.09+ ampere to produce 
the desired incandescence. It will be remembered that the watt 
is a volt-ampere and the 10-watt lamp will then require 

110 volts X 0.09 + ampere = 10 watts. 

Since 10-watt lamps are the smallest units that may be used 
on 110-volt circuits, their employment in smaller sizes must be 
such as will give more stable filaments. This is possible when the 
lamps are used at lower voltage. A 10-watt lamp on a 10-volt 
circuit will require an ampere of current. 

10 volts X 1 ampere = 10 watts. 

A filament suitable for an ampere of current is shorter and 
heavier than that of the 110-volt lamp and therefore furnishes a 
good form of construction. Still lower voltages may be used 
with filaments suited to the quantity of light desired. 

In the case of battery lamps that are intended to operate on 1 
or more volts, the filaments are made in size and length to suit 
the condition of action. In all cases the product of the volts and 
amperes give the capacity of the lamp in watts. 

Miniature lamps are ordinarily marked to show the voltage on 
which they are intended to operate. A 6-volt battery lamp is 



326 MECHANICS OF THE HOUSEHOLD 

intended to be used with a primary battery of four to six cells de- 
pending on the condition of usage, or three cells of storage bat- 
tery, each cell of which gives 2 VjDlts of pressure. 

Flash Lights. — These are portable electric lamps composed of 
a miniature incandescent bulb, which with one or more dry cells 
are enclosed in a frame to suit the purpose of their use. They are 
made in pocket sizes or in form to be conveniently carried in the 
hand and are convenient and efficient lamps wherever a small 
amount of light is required for a short time. The electricity for 
operating the lamp is supplied by a battery of dry cells (to be 
described later), or by a single dry cell. In each case the in- 
candescent bulb is suited to the voltage of the battery. 

In replacing the bulbs care must be taken to see that the volt- 
age is that suited to the battery. The voltage is usually stamped 
on the lamp base or marked on the bulb. In case a lamp in- 
tended for a single cell is used with a battery of three or four 
cells, the lamp filament will soon be destroyed. The reverse 
will be true should a lamp intended for a battery be used with a 
single cell. The single cell giving not much more than a volt 
of electromotive force will not send sufficient current through 
the lamp filament to render it incandescent. 

The Electric Flat-iron. — The changes that have been made in 
domestic appliances by the extended use of electricity have 
brought many innovations but none are more pronounced than 
the improvements made in the domestic flat-iron. It was the 
first of the household heating devices to receive universal recogni- 
tion ^nd its place as a domestic utility is firmly established. 

The relatively high cost of heat as generated through electric 
energy is in a great measure counterbalanced in the flat-iron by 
high efficiency in its use. In the electric iron, the heat is de- 
veloped in the place where it can be used to the greatest advan- 
tage, and transmitted to the face of the iron with but very little 
loss. Because of this direct application the cost of operation is 
but slightly in excess of the other methods of heating. 

The electric flat-iron has now become a part of the equipment 
of every commercial laundry, where electricity can be obtained 
at a reasonable rate. The popularity of the electric iron is due 
to its cleanliness and to the increased amount of work that may 
be accomplished through its use. Because of the time saved in 



ELECTRICITY 



327 



changing irons and the comfort of the room by reason of its lower 
temperature, a sufficiently greater amount of work is accom- 
plished to more than compensate for the greater cost of heat.l 

The electric current is conducted to the flat-iron from the 
house circuit by wires made into the form of a flexible cord. 
The cord attaches to the electric-lamp fixture by a screw-plug 
and connects with the iron by a special attachment piece as in- 
dicated at P and R in Fig. 226. Connection is made to an in- 
candescent lamp socket at any convenient place. The only pre- 
caution necessary in attaching the 
iron is to see that the fuse and the 
wires, which form the circuit, are of 
size sufficient to transmit the amount 
of current the iron is rated to use. 
As explained later, the fuse which is 
a part of every electric house circuit, 
and the conducting wires which form 
the heater circuit, must be sufficient 
in size to transmit the necessary cur- 
rent without material heating. 

The cord connects with the socket 
at P, and the current turned on. 
It is attached with the iron by a 
piece i2, made of non-conducting and 
heat-resisting material and arranged 
to make contact with the heater 
terminals by two brass plugs that 
are insulated from the body of the 
iron and afford easy means of making 
electric contact. The contact plugs 

are shown in Fig. 227. To make electric connection, the con- 
tact piece is simply pushed over the plugs, where it is held in 
place by friction. Instructions which accompany a flat-iron 
when purchased advise that the attachment piece be used in 
turning off the current. The reason for this is because of the 
flash that accompanies the bieak in the circuit when disconnec- 
tion is made in the socket. This flash is really a small electric 
arc, that forms as the circuit is broken and which burns away 
the switch at the point of disconnection. The arc so formed 




Fig. 



226. — Electric flat-iron and 
its attachments. 



328 



MECHANICS OF THE HOUSEHOLD 



burns away the contact pieces in the switch and it is soon de- 
stroyed. The attachment piece will stand this wear more readily 
than the socket switch and hence is preferable for disconnect- 
ing. The irons are frequently provided with a special switch 
for the service required in the flat-iron. 

A spiral spring connected to the attachment cord prevents 
it from kinking when in use and thus breaking the conducting 
wires. The attachment cord is made of stranded wires to make it 
flexible. The strands of fine copper wire are made to correspond 



Large, Comfortable, Always 
Cool Wood Handle 



Electrically Welded Steel 
Handle Supports, no Screws 
or Eivets to Work Loose 



Beautiful Nickel Finish, 
Highly Polished Attractive, 
Prevents Rust 



Cut Away Nose 
makes Ironing Easier [' 



Durable, Composition 
Switch Plug, Always 
Cool Enough to Handle 



Pressure Plate, Machine 
Milled, Keeps Heat in 
Bottom of Iron 



Bolts which Clamp 
Pressure Plate, 
Element and Bottom 
into Practically 
One Solid Mass 



Indestructible, Patented 
Sheathed Heating 
Element, Fool Proof 



Extra Large Ironing 
Surface, Smooth as Glass 




Non-kink Spring, 
Protects Cord 



Eemovble Plug Guard 
Acts as a Guide for 
Putting Plug in Position 



German Silver, Non-Corroding 
Round, Removable Contacts 



Riveted Connections, cannot 
Break or Crack Ribbon 



Genuine India 
Mica Insulation 



Bottom Plate, Machine Milled, and 
Ground Perfectly Smooth on both Sides 



Fig. 227. — Electric flat-iron showing position of the heating element and contact 

plugs. 



to the gage numbers by which the various sizes of wire are des- 
ignated. In use the constant movement of the iron tends to 
kink the cord and thus breaks the strands. This action is most 
pronounced at the point where the cord attaches to the iron. 
For this reason a spiral spring wire encloses the cord for a short 
distance above the attachment piece. After long usage the cord 
is apt to break in this vicinity. It may usually be repaired by 
cutting off the ends of the cords and new connections made in 
the attachment piece. When the iron is in use the slack por- 
tion of the cord is kept from interfering with the work by the 



ELECTRICITY 



329 



coiled wire >S, which connects with the cord at any convenient 
place. 

Electric flat-irons are made in a variety of styles and forms, 
the mechanism of each possessing some particular advantage, but 
all are provided with the same essential parts, chief of which 
is the heater with its electric attachment piece. In Fig. 228 
is shown very clearly the construction of an example in which 
attention is called to the points of excellence that are required 
in a particularly serviceable iron. The form of the heating ele- 
ment which is recognized in the iron is also shown in Fig. 288. 

In the figure the heater is made of coils of resistance wire, 
wound on a suitable frame of mica. The heating element is in- 
sulated from the body of the iron with sheets of mica, this being 
a material that makes an excellent insulator and is not materi- 





^^^^:^YXVn\W\WXX^ 


SFm+^r^^ 


^<rrr\ 


:_=__= = 


^ 




mU 


. -. _ 


EE = :E = :~- 


/<Wl=E 




Mica r 

ll 


! mi 


K -'=ii 


^n\^ 


"S 1 1 




mYTiII (.1 




x^^ 




1 1 mi 


eater Coils 


^^^" 




zl'zl--__. 


Mica Insulation ^^"^ 


•-JJJrJrU^' ! ' rrl^ 


g^yii^ 



ally affected by the heat to which it is subjected. The resist- 
ance wire of which the element is composed is especially prepared 
to resist the corroding action common to metal when heated in air. 
The form of the element is such as to permit the least movement 
of the turns of wire — in their constant heating and cooling — that 
will allow the different spires to make contact and thus change 
the resistance. Should the spires of wire come together, the 
current would be shunted across the contact and the resistance 
of the element decreased. The effect of such a reduction of re- 
sistance would be an increased flow of current and a correspond- 
ing increase of heat. In this, as in the electric lamp and all other 
electric circuits, the current, voltage and resistance follow the 
conditions of Ohm^s law. 



330 MECHANICS OF THE HOUSEHOLD 

Different sizes of irons will, of course, require different amounts 
of current. A 6-pound iron, such as is commonly used for house- 
hold work, will take about 5 amperes of current at 110 volts 
pressure. The amount of electricity the iron is intended to 
consume is generally stamped on the nameplate of the manu- 
facturer. This is specified by the number of volts and 
amperes of current the iron is rated to use. As an example, 
the iron may be marked. Volts 105-115, Amperes 2-3. This 
indicates that the iron i^ intended to be used on circuits that 
carry electric pressure varying from 105 to 115 volts and that 
the heater will use from 2 to 3 amperes of current, depending 
on the voltage. 

To estimate the cost of operating such an iron, it is neces- 
sary to determine the number of watts of electric energy consumed. 
The number of watts of energy developed under any condition 
will be the product of the volts times the amperes. Suppose that 
in the above example the iron was used on a circuit of 110 volts. 
Under this condition the current required to keep the iron hot 
would be 2.5 amperes. The product of these two qualities, 110 
X 2.5 is 275 watts. If the cost of electricity is 10 cents per 
kilowatt-hour (1000 watts) the cost of operating the iron would 
be 

275 X 10 cents =. 2% cents an hour. 

lOTO . 

Since the electric iron requires a much larger amount of cur- 
rent than is usually required for ordinary lighting, the circuit 
on which it is used should receive more than passing attention. 
The wires should be of size amply large to carry without heating 
the current necessary for its operation. This topic will be dis- 
cussed later but it is well here to call attention to the necessity 
for a circuit suited to the required current. If an iron requir- 
ing 5 amperes of current is attached to a circuit that is intended to 
carry only 3 amperes the conducting wires will be overheated 
and may be the cause. of serious results. 

The Electric Toaster. — As shown in Fig. 229 the toaster is 
made of a series of heating elements mounted on mica frames and 
supported on a porcelain base. It is an example of heating by 
exposed wires and direct radiation. The heaters H are coils of 



ELECTRICITY 



331 



flat resistance wire that are wound on wedge-shaped pieces of 
mica. They are supported on a wire frame that is formed to re- 
ceive sHces of bread on each side of the heaters. The attach- 
ment piece A and the material of the heater is similar in con- 
struction to that of the flat-iron. The electric circuit may be 
traced from the contacts at A and B in the attachment plug by 
the dotted lines which indicate the wires in the porcelain base. 
The current traverses each coil in turn and connects with the 
next, alternately at the top and bottom. The resistance is such 
as will permit the voltage of the circuit to send through the coils 




Fig. 229. — The electric toaster. 



current sufficient to raise the heaters to a red heat. The added 
resistance of the hot wires decreases the flow of current to keep 
the temperature at the desired degree. 

In a heater of this kind the resistance of the wire may in- 
crease with age and the coils fail to glow with a sufficient bright- 
ness. The reason for the lack of heat is that of decrease in current, 
due to the increased resistance of the wires. This condition may 
be corrected by the removal of a little of the heater coils. If a 
turn or two of the heater wire is removed, the resistance of the 
circuit is reduced and the effect of the increased current will 
produce a higher temperature in the heater. 



332 MECHANICS OF THE HOUSEHOLD 

Motors.— As a means of developing mechanical power in small 
units, the electric motor has made possible its application in 
many household uses that were formerly performed entirely by 
manual labor. As a domestic utility electrical power is generated 
at a cost that is the least expensive of all its applications. 
As a means of lighting and heating electricity has had to compete 
with established methods and has won place because of the advan- 
tages it possesses over that of cost. In the development of 
domestic power it has practically no opponent. There is no other 
form of power that can be so successfully utilized in delivering 
mechanical work for the purposes required. A kilowatt of 
electric energy, for which 10 cents is a common price, will furnish 
a surprising amount of manual labor. Theoretically, 746 watts 
is equal to 1 horsepower. The commercial kilowatt is rated at 
an hour of time, and is, therefore, equal theoretically to 1}/^ 
horsepower for one hour. While motors cannot be expected to 
transform all of this energy into actual work without loss, even 
at the low rate of efficiency attained by the small electric mo- 
tor, they furnish power at a relatively small cost. 

The first applications of electric power were those for sewing 
machines, fans, washing machines, etc. Its use has made pos- 
sible the vacuum cleaner, automatic pumping, refrigeration, 
ventilation, and many other minor uses as the turning of ice- 
cream freezers, churning and rocking the cradle. 

Electric motors are made in many sizes for power generation 
and in forms to suit any application. They are made to develop 
3^^o horsepower and in other fractional sizes for both direct 
and alternating current. 

In applying mechanical power to any particular purpose 
special appliances must be made to adopt electric motors to the 
required work. This is accomplished in all household require- 
ments. The motors are made to run at a high rate of speed and 
must be reduced in motion by pulleys or gears to suit their con- 
dition of operation. As in the case of electric lamps they must 
be suited to the voltage and type of current of the circuit on 
which they are to be used. 

Commercial electric circuits furnish electricity in two types, 
direct current, ordinarily termed D.C., and A.C. or alternating 
current. The terms direct and alternating current apply to the 



ELECTRICITY 333 

direction of the electric impulses which constitute the transmitted 
energy. In the electric dynamo, the generation of the current 
is due to impulses that are induced in the wires of the dynamo 
armature as they pass through a magnetic field of great intensity. 
These electric impulses are directed by the manner in which the 
wires cut across the lines of force which make up the magnetic field. 
In the case of the direct current the impulses are always in the 
same direction through the circuit, while in the other they are in- 
duced alternately to and fro and so produce alternating current. 

The term electric current is used only for convenience of ex- 
pressing a directed form of energy. Since nothing really passes 
through the wires but a wave of energy, the effect is the same 
whether the electric impulses are in the same or in opposite di- 
rections. An incandescent lamp will work equally well on an 
A.C. or a D.C. circuit of the proper voltage; but in the case of mo- 
tors the form of construction must be suited to the kind of cur- 
rent. Both A.C. and D.C. commercial circuits are in common use, 
the units of measurement are the same for each but in ordering a 
motor it is necessary to state the type of current and the voltage, 
in order that the dealer may supply the required machine. In 
the case of an alternating motor it is further necessary to state 
the number of cycles of changes of direction made per second 
in the A.C. circuit. All of this information may be obtained by 
inquiring of a local electrician or of the power station from which 
the current is obtained. 

There is still another item of information necessary to be 
supplied with an order for a motor, other than those of fractional 
horsepower. With motors of a horsepower or more it is necessary 
to state the number of phases included in the circuit. This 
information to be complete must state whether the motor is 
to operate on a single-phase, two-phase, or three-phase circuit. 
These terms apply to a condition made possible in A.C. generation 
that permits one, two, or three complete impulses to be developed 
in a circuit at the same time. These phases are transmitted 
by three wires, any two of which will form a circuit and give a 
supply of energy at the same voltage. Either one phase or all 
may be used at the same time and for this reason the phase of an 
A. C. motor should be given in an order. To make the information 
complete there should be included the number of cycles or com- 



334 MECHANICS OF THE HOUSEHOLD 

plete electric impulses per second produced in the circuit. Sup- 
pose that a 1-horsepower motor is required to work on an A.C. 
circuit of 110 volts. Inquiry of the electric company reveals 
that the circuit is three-phase at 60 cycles per second. The 
dealer on receiving this information will be able to send a motor 
to suit your conditions. Most A.C. motors of 1 horsepower or 
less are of the single-phase variety. In the case of D.C. motors 
it is necessary only to state the voltage of the circuit to make 
the required information complete. 

Fuse Plugs. — Every electric circuit is liable to occurrences 
known as short-circuiting or ^^ shorting.'' This is a technical 
term describing a condition where, by accident or design, the 
wires of a circuit are in any way connected by a low-resistance 
conductor or by coming directly into contact with each other. 
In case of shorting, the resistance is prax^tically all removed and 
the amount of current which flows through the circuit is so great 
as to produce a dangerous amount of heat in the wires. If the 
covering of a lamp cord becomes worn so as to permit the bare 
wire of the two strands to come together, a ^^ short'' is produced. 
Immediately, the reduced resistance permits the electric pressure 
to send an amount of current through the wires, greater than they 
are intended to carry. When this occurs an electric arc will 
form at the point of contact with the accompanying flash of 
vaporizing metal and the wire will ' finally burn off. Fires 
started from this cause are hot uncommon. 

To guard against accidents from short-circuiting, every elec- 
tric circuit should be provided with fuses which, in cases of emerg- 
ency, are intended to melt and thus break the circuit. Fuses 
are made of lead-composition or aluminum and are used in the 
form of wire or ribbon-like strips, of sizes that will carry a definite 
amount of current. They are designated by their carrying 
capacity in amperes. As an example: a 2-ampere fuse will 
carry 2 amperes of current without noticeable heating, but at a 
dangerous overload the fuse will melt and the circuit be broken. 
Should a short-circuit be formed at any time, the rush of current 
through the fuse will cause it almost immediately to melt, and 
stop the flow of current. They are, therefore, the safeguard of 
the circuit against undue heating of the conducting wires. 

When an open fuse blows (melts), the heat generated by the 



ELECTRICITY 



335 



arc, formed at the breaking circuit, is so sudden that there is 
frequently an explosive effect that throws the melted metal in 
all directions, and in case it comes into contact with combustible 
material a fire may result. To do away with this danger, fire 
insurance companies in their specifications of electric fixtures 
state what forms of fuses will be acceptable in the buildings to be 
insured. These specifications are known as the Underwriters 
Rules and may be obtained from any fire insurance company. 
The fuses, or fuse plug, as they are commonly called, generally 
occupy a place in a cabinet or distributing panel, near the point 
where the lead wires enter the building. The cabinet contains 
the porcelain cutouts for sending the current through the different 
circuits; the fuse plugs form a part of the cutouts, one fuse to each 
wire. The cabinet contains be- 
sides the cutouts a double-poled 
switch to be used for shutting 
off the current from the build- 
ing when desired. 

Cabinets for this purpose are 
made in standard form of wood 
or steel to suit the condition of 
service. These cabinets may be 
obtained from any dealers in 

electrical supplies or the cabinet may be made a part of the 
house since they are only small shallow closets. Fig. 230 rep- 
resents such a cabinet as is used in the average dwelling. It 
is made of a light wooden frame set between the studding of a 
partition at any convenient place. The bottom of the cabinet 
is made sloping to prevent its being used as a place of storage 
for articles that might lead to trouble. The cabinet is sometimes 
lined with asbestos paper as a prevention from fire but this is 
not necessary as the fuse plugs and their receptacles, when of 
approved design, are sufficient to prevent accident. 

The main wires which supply the house with electricity — 
marked lead wires — are brought into the cabinet as shown in 
Fig. 231 and attached to the poles of the switch S, In passing 
through the switch the lead wires each contain a mica-covered 
fuse plug F, that will be described later. The current at any time 
may be entirely cut off from the house by pulling the handle H, 




Fig. 230. — Electric cabinets. 



336 



MECHANICS OF THE HOUSEHOLD 



which is connected by an insulating bar and the contacts N of 
the switch. When the handle H is pulled to separate the contact 
pieces, all electric connection is severed at that point. 

The wattmeter for measuring the current is placed at the 
points marked meter , as a part of the main circuit. The main 
wires in the cabinet terminate in the porcelain cutouts, from 
which are taken off the various circuits of the house. In the 
figure, three such cutouts are shown making three circuits marked 




Lead Wires 
Fig. 231. — Electric panel containing cutout blocks, fuses and switch. 

1, 2, and 3. In circuit No. 1, the fuses are marked F. These 
wires"are joined to the main wires at the points marked C and C. 
The number of circuits the house will contain depends on the 
number of lights and the manner in which they are placed. The 
circuits are intended to be arranged so that in case of a short, 
no part of the house will be left entirely in darkness. 

Fuses for general use are made in two different types — the 
plug type and the cartridge type — each of which conforms to the 
rules of the Underwriters Association. Those most commonly 



ELECTRICITY 



337 



used for house wiring are the plug type shown in Fig. 232 and 
indicated in the figure just described. These plugs are made of 
porcelain and provided with a screw base which permits their be- 
ing screwed into place like an incandescent lamp. The front of 
the plug is arranged with a mica window which allows inspection 
to be made in case of a short, the blown fuse indicating the cir- 
cuit in which the trouble is located. Another style of the same 
type of plug, known as the re-fusable fuse plug, permits the fuse 
to be replaced after the wire has been destroyed by a short. 

The second type is commonly known as the cartridge fuse plug 
from its general appearance. This fuse is shown in Fig. 233. 






In f\'im 




Fig. 232. — Mica cov- 
ered fuse plug. 



Fig. 233.— Cartridge fuse. 



Fig. 234.— Plug re- 
ceptacle for cartridge 
fuse. 



The f usable wire is enclosed in a composition fiber tube, the 
ends of which are covered by brass caps which afford contact 
pieces in the fuse receptacle and to which are fastened the ends 
of the fuse wire. These fuses are very generally employed in 
power circuits and others of large current capacity. The small 
circle in the center of the label is the indicator. When the fuse 
burns out, a black spot will appear in the circle. • It is sometimes 
desirable to use the cartridge fuse plug in receptacles intended 
for the mica-covered type. The use of the cartridge fuses under 
this condition is effected by use of a porcelain receptacle such as 
is shown in Fig. 234; the cartridge fuse is simply inserted into the 
receptacle which is then screwed into the socket in place of the 
mica fuse. 

In order to avoid any possible chance of overloading the wires 
of a circuit, fuses are installed which are suited to the work to be 
performed. Suppose that there are ten 40-watt lamps that may 



22 



338 MECHANICS OF THE HOUSEHOLD 

be used on a circuit, each lamp of which requires ^f i ampere 
of current. 

110 X C = 40 watts 

kj = YYpj = YY ampere per lamp. 

Ten such lamps require ten times ^{i ampere or ^%i =3.7 
amperes to supply the lamps. 

A fuse that will carry 3.7 amperes of current will supply the 
circuit but a 5-ampere fuse will permit an increase in the size 
of the lamp and will fulfill all the necessary conditions. If, 
however, an electric heater requiring 7 amperes were attached to 
the circuit, the fuse being intended for only 5 amperes would soon 
burn out. When a fuse burns out it must be replaced either with 
an entirely new receptacle or the fuse wire must be replaced. 

It sometimes happens that in case of a blown fuse there is no 
extra part at hand and a wire of much greater carrying capacity 
is used in its place. It should be remembered that in this prac- 
tice of ^'coppering'' a blown fuse, has taken away the protection 
against short-circuiting with its possibility of mischief. 

When a short occurs, the cause should be sought for. It 
cannot be located and on being replaced a second fuse blows, the 
services of an electrician should be secured. 

Electric Heaters. — All electric heating devices — whether in 
the form of hot plates, ovens, stoves or other domestic heating 
apparatus — possess heating elements somewhat similar to the flat- 
iron or the toaster. The construction of the heating element will 
depend on the use for which the heater is intended and the tem- 
perature to be maintained. Hot plates similar to that of Fig. 
235 are made singly or two or more in combination. When the 
heat is to be transmitted directly by radiation the heating coils 
are open, as with the toaster. Under other conditions the coils 
are embedded in enamel that is fused to a metal plate. In 
elements of this kind the heat is transmitted to the plate entirely 
by conduction from which it is utilized in any manner requiring 
a heated surface. The form of the heating element will, therefore, 
depend on the application of the heat, whether it is by direct 
radiation or by a combination of radiation and conduction. 

Electric ovens are constructed to utilize electric heat in_an 
insulated enclosure. Heat derived from electricity is more 



ELECTRICITY 



339 



expensive than from other sources but when used in insulated 
ovens it may be made to conveniently perform the service of that 
derived from other fuels. In electric ovens the heaters are 
attached to inside walls. As in other heating elements they are 
arranged to suit the conditions for which the oven is to be used. 
The heaters are usually so divided as to permit either all of the 
heaters to be used at the same time to quickly produce a high 
temperature, or only a portion of the heat to be used in keeping 
up the temperature lost by radiation. Ovens of this kind may be 
provided with regulators by means of which the heat may be 
automatically kept at any desired temperature. Such heating 
and temperature regulation may be used to produce any desired 
condition, but in practice the cost of the heat is the factor which 
determines its use. Unless electric heat is conserved by insula- 
tion it cannot become a competitor with other forms of heating. 




Fig. 235. — Electric three-burner hot plate. Electric hot plate. 



Electric cooking stoves and ranges are made for every form of 
domestic and cuUnary service. They fulfill many purposes that 
may be obtained in no other way. As conveniences, the cost of 
heat becomes of secondary consideration and their use is con- 
stantly increasing. In Fig. 236 is an example of a time-controlled 
and automatically regulated electric range. In the picture is 
shown separately all of the heaters for the ovens and stove top. 
The part >S shows the switches attached to the heaters of 
the stove top, which is raised to show the connecting wires. In 
the larger oven there are two heaters of 1000 watts each, and in 
the smaller oven one heater of 850 watts. Each heater may be 
controlled separately with a switch giving three regulations of 
heat — high, medium and low. The advantage of this arrange- 
ment lies in the fact that one can set the two heaters in the oven 
at different temperatures which will permit either a slow or quick 



340 



MECHANICS OF THE HOUSEHOLD 



heat, but when the predetermined temperature is reached the 
current will be automatically cut off by the circuit-breakers. 
Such flexibility of heat control in the ovens permits the operator 
to apply heat at both top and bottom for baking and roasting 
at just the desired temperature. This arrangement also avoids 
the danger of scorching food from concentration of heat, and 
warping utensils or the hnings of the oven. All oven heaters on 




Fig. 236. — Electric range. 



Showing how all parts can be removed for cleaning 
and replacement. 



the automatic ranges are further controlled and mastered by the 
circuit-breakers. 

Intercommunicating Telephones. — This form of telephone is 
used over short distances such as from room to room in buildings 
or for connecting the house with the stable, garage, etc. It is 
complete, in that it possesses the same features as any other 
telephone but the signal is an electric call-bell instead of the 
polarized electric bell used in commercial telephone service. 



ELECTRICITY 



341 



Any telephone is made to perform two functions: (1) that of 
a signal with which to call attention; and (2) the apparatus 
required to transmit spoken words. In the intercommunicating 
telephone or interphone, the signal is made like any call-bell and 
parts are similar to those described under electric signals. The 
bell-ringing mechanism is included in the box with the trans- 
mitting apparatus and the signal is made by pressing a push 
button. It is not suitable for connecting with public telephones. 
Telephone companies, as a rule, do not permit connection with 
their lines any apparatus which they do not control. 

The interphone of Fig. 237 shows the instrument complete 
except the battery. This form of instrument is inexpensive, 
easy to put in, simple to operate and sup- 
plies a most excellent means of intercom- 
munication. Complete directions for in- 
stallation are supplied with the phones by 
the manufacturers. 

Electric Signals. — Electrical signaling de- 
vices for household use, in the form of bells 
and buzzers, are made in a great variety of 
forms and sizes to suit every condition of 
requirement. The vibrating mechanism of 
the doorbell is used in all other household 
signals except that of the magneto tele- 
phone. It is an apphcation of the electromagnet, in which 
the magnetism is applied to vibrate a tapper against the rim 
of a bell. 

A bell system consists of the gong with its mechanism for 
vibrating the armature, an electric battery or A.C. transformer 
connected to the magnet coils to form an electric circuit and a 
push button which serves to close the circuit whenever the 
bell is to be sounded. The bell system is an open-circuit form 
of apparatus; that is, the circuit is not complete except during 
the time the bell is ringing. By pressing the push button the 
circuit is closed and the electric current from the battery flows 
through the magnet and causes the tapper to vibrate. When the 
push button is released the circuit is broken and the circuit 
stands open until the bell is to be again used. The parts of the 
bell mechanism are shown in Fig. 238 where with the battery, 




Fig. 237.— The in- 
tercommu nicating 
telephone. 



342 



MECHANICS OF THE HOUSEHOLD 



the push button and the connecting wires is shown a complete 
doorbell outfit. These parts may be placed in different parts of 
the building and connected by wires as shown in the Fig. 239. 
The bell is located at E, in the kitchen. The battery is placed 
in the closet at B, the connecting wires are indicated by the heavy 
lines; they are secured to any convenient part of the wall and 
extend into the basement and are fastened to the joists. The 
wires terminate in the push button P, where they pass through 
the frame of the front door. The wires are secured by staples 
to keep them in place. Each wire is fastened separately to avoid 
the danger of short-circuiting. If both wires are secured with a 
single staple there is a possibility of the insulation being cut and a 
short produced across the staple. 

The battery B^ in Fig. 238, is a single dry cell but more com- 
monly it is composed of two dry cells joined in series. It is con- 




FiG. 238. — Diagram showing the parts of an electric doorbell. 

nected, as shown in the figure, to the binding posts Pi and P2 of 
the vibrating mechanism, the push button PB serving to make 
contact when the circuit is to be closed. When the button is 
pressed the circuit is complete from the + pole of the battery 
cell through the binding post Pj, across the contact P, through 
the spring A, through the magnet coils M, across the binding 
post P2 and push button to the — pole of the cell. The vibration 
of the tapper is caused by the magnetized cores of the coils M, 
When the electric current flows through the coils of wire, the iron 
cores become temporary magnets. This magnetism attracts 
the iron armature attached to the spring A, and it is suddenly 
pulled forward with energy sufficient to cause the tapper to strike 
the gong. As the armature moves forward, the spring contact 
at P is broken and the current stops flowing through the magnet 



ELECTRICITY 



343 



coils. When the current ceases to flow in the magnet coils, the 
cores are demagnetized and the armature is drawn back by the 
spring A to the original position. As soon as the contact is 
restored at /^ a new impulse is received only to be broken as 
before. In this manner the bell continues ringing so long as the 
push button makes contact. The screw at F is adjusted to suit 
the contact with the spring attached to the armature. The 
motion of the armature may be regulated to a considerable 




-jr "r -r ~r ~r -|i 



Fig. 239. — Example of an electric doorbell installation. 



degree by this adjustment. When properly set the screw is 
locked in place by a nut and should require no further 
attention. 

Electric bells vary in price according to design and work- 
manship. A bell outfit may be purchased complete for $1 but 
it is advisable to install a bell of better construction, as few pieces 
of household mechanism repay their cost in service so often as a 
well-made bell. The bell should be rigid, well-constructed, and 
the contact peice F should be adjustable. This part F, being 



344 



MECHANICS OF THE HOUSEHOLD 



the most important of the moving parts of the bell, is shown sepa- 
rately in Fig. 240. Only the ends of the magnet coils with their 
cores are shown in the figure. The contact is made at ^, by the 
pressure of the spring against the end of the adjustable screw D. 
When the screw is properly adjusted it is locked securely in place 
by the nut (?. The screw D is held with a screw-driver and the 
nut G forced into position to prevent any movement. If the 
screw is moved, so that contact is lost at A, the bell will not ring. 
In the better class of bells the point of the screw and its contact 

at A are made of platinum 
to insure long life. With 
each movement of the 
armature a spark forms at 
the contact which wears 
away the point, so that to 
insure good service these 
points must be made of 
refractory material. 

Buzzers. — Electric bells 
are often objectionable as 
signal calls because of their 
clamor, but with the re- 
moval of the bell the vi- 
brating armature serves 
equally well as a signal but 
without the undesirable 
noise. With the bell and 
tapper removed the operat- 
ing mechanism of such a device works with a sound that has 
given to them the name of buzzers. Fig. 241 illustrates the 
form of an iron-cased buzzer for ordinary duty. The working 
parts are enclosed by a stamped steel cover that may be easily 
removed. The mechanism is quite similar to that already de- 
scribed in the doorbell and Fig. 240 shows in detail the work- 
ing parts. The noise, from which the device takes its name, is 
produced by the armature and spring in making and breaking 
contact. 

Burglar Alarms. — A burglar alarm is any device that will 
give notice of the attempted entrance of an intruder. It is 




Fig. 240. — Diagram of the vibrating mech- 
anism used in buzzers and doorbells. 



ELECTRICITY 



345 



usually in the form of a bell or buzzer placed in circuit with a 
battery, as a doorbell system, in which the contact piece is 
placed to detect the opening of a door or window. The contact 
is arranged to start the alarm whenever the window or door is 
opened beyond a certain point. The attachment shown in Fig. 
242 is intended to form the contact for a window. It is set in the 
window frame so that the lug C will be depressed and close the 
alarm circuit in case the sash is raised sufficiently to admit a man. 
Each window may be furnished with a similar device and the 
doors provided with suitable contacts which together form a 
system to operate in a single alarm. During the time when the 
alarm is not needed it is disconnected by a switch. The windows 




FIG.24I 



FIG .24-5 



FIG.242 
Fig. 241. — The electric buzzer. 
Fig. 242. — Contact for a window burgier alarm. 
FjG. 243. — Trip contact which announces the opening of a door. 
Fig. 244.- — Contact for a door alarm. 
Fig. 245. — Doorway or hall matting with contacts for electric alarm. 

and doors are sometimes connected with an annunciator which 
will indicate the place from which an alarm is given. An annun- 
ciator used for this purpose designates the exact point at which 
the contact is made and removes the necessity of searching for 
the place of attempted entrance. 

In Fig. 243 is illustrated one form of door trip which may be 
used on a door to announce its opening. This trip makes elec- 
tric connection in the alarm circuit when the opening door comes 
into contact with the swinging piece T, but no contact is made as 
the door closes. The trip is fastened with screws at D to the 
frame above the door. The opening door comes into contact with 
T and moves it forward until the electric circuit is formed at C; 
after the door has passed, a spring returns it to place. As the 



346 MECHANICS OF THE HOUSEHOLD 

door is closed, the part T is moved aside without making elec- 
tric contact. 

Fig. 244 is another form of door alarm that makes contact when 
the door is opened and remains in contact until the door is closed. 
The part P is set into the door frame of the door in such position 
that the contact at C is held open when the door is closed. 
When the door is opened a spring in C closes the contact and 
causes the alarm to sound. It continues to sound until the door 
is closed and the contact is broken. When the use of the alarm 
is not required, the contact-maker is turned to one side and the 
contact is held open by a catch. It is put out of use by pressing 
the plunger to one side. 

The matting shown in Fig. 245 is provided with spring contacts 
so placed that no part may be stepped upon without sounding 
the alarm. When placed in a doorway and properly connected 
with a signal, no person can enter without starting an alarm. The 
matting is attached to the alarm by the wires C and contacts 
are set at close intervals so that a footstep on the mat must 
close at least one contact. 

Annunciators. — It is often convenient for a bell or buzzer to 
serve two or more push buttons placed in different parts of the 
house. In order that there may be means of designating the 
push button used — when the bell is rung — an annunciator is pro- 
vided. This is a box arranged with an electric bell and the 
required number of pointers and fingers corresponding to the 
push buttons. In Fig. 246 is shown an annunciator with 
which two push buttons are served by the single bell. The 
annunciator is placed at the most convenient place of observa- 
tion, usually in the kitchen. When the bell rings the pointer 
indicates the push button that has last been used. In hotels or 
apartment houses an annunciator with a single bell may thus 
serve any number of push buttons. In a burglar-alarm system 
the annunciator numbers are arranged to indicate the windows and 
other openings at which entrance might be made. When the 
alarm sounds the annunciator indicates the place from which the 
alarm is made. 

Table Pushes. — Call bells to be rung from the dining-room 
table are connected with an annunciator or to a separate bell. 
The table pushes may be temporarily clamped on the edge of the 



ELECTRICITY 



347 



table and connected by a cord to an attachment set in the floor 
or the connection may be made by a foot plate set on the floor. 
In Fig. 247 is shown a form of push P which is intended to be 
clamped to the edge of the table under the cloth. The plate F 
forms the floor connection. It is set permanently with the up- 
per edge flush with the surface of the floor. The part aS, in which 
the connecting cord terminates, when inserted in the floor plate, 
makes contact at the points C to form an electric circuit with 
the battery. The foot plate shown in Fig. 248 is only an enlarged 
push button which is set under the table in convenient positions 
to be pressed with the foot. Its connection might be made as 




FIG. 246 



FIG. 249 
Fig. 246. — A kitchen annunciator. 

Fig. 247. — Plug attachment and table push for a dining table. 
Fig. 248. — Foot plate and contact for table bell. 
Fig. 249. — Call bell attachment with detachable contact piece. 



indicated or with the same floor connection as that of the pre- 
ceding figure. Fig. 249 is a simpler form of floor push in which a 
metallic plug is inserted in the floor place. When the plug R 
is pressed, contact is made at the points C to form the circuit 
with the battery and bell. 

Bell-ringing Transformers. — The general employment of al- 
ternating electricity for all commercial service requiring dis- 
tant transmission is because of the possibiUty of changing the 
voltage to suit any condition. The energy transmitted is de- 
termined by the amperes of current carried by the wires and the 



348 MECHANICS OF THE HOUSEHOLD 

volts of pressure by which it is impelled. The product of these 
two factors determines the watts of energy transmitted. 

110 volts X 1 ampere =110 watts. 

If the voltage is raised to say ten times the original intensity 
with the same current, the quantity of energy is ten times the 
original amount. 

1100 volts X 1 ampere = 1100 watts. 

The carrying capacity of wires is determined by the amperes 
of current that can be transmitted without heating. 

The cost of copper wire is such that the expense of large wires 
for carrying a large current is unnecessary where by raising the 
voltage a small wire will perform the same service; therefore, it is 
desirable to transmit electric energy at a high voltage and then 
transform it to suit the condition of usage. 

Alternating current may be transformed to a higher or a lower 
voltage to suit any condition by using step-up or step-down 
transformers. 

A transformer is a simple device composed of two coils of wire 
wound on a closed core of iron. The coil into which is sent the 
inducing current is the primary. That in which the current is 
induced is the secondary coil. The change in voltage between 
primary and secondary coils vary as the number of turns of wire 
which compose the coils. The house circuit may be stepped 
down from the customary 110 volts to a voltage such as is fur- 
nished by a single dry cell, or a battery of cells. 

In principle, the action of the transformer is the same as that 
of the induction coil, a detailed explanation of which will be found 
in any text-book of physics. Each impulse of current in the 
primary coil of the transformer magnetizes its core and the mag- 
netism thus excited induces a corresponding current in the 
secondary coil. Since alternating current in the primary coil 
constantly changes the polarity of the core, each change of mag- 
netism induces current in the secondary coil. 

Small transformers are frequently used for operating doorbells, 
annunciators, etc., in place of primary batteries. These trans- 
formers are also used to supply current for lighting low-power 
tungsten lamps that cannot be used with the ordinary voltages 



ELECTRICITY 



349 



employed in house lighting. The primary wires of the trans- 
former are attached to the service wires in the house and from 
the secondary wires voltages are taken to suit the desired purposes. 
Fig. 250 shows such a transformer with the cover partly 
broken away to expose the interior construction. The wires 
from house mains MM lead the current to the primary coil P 
which is a large number of turns of fine wire wound about a soft- 
iron core. The induced current in the secondary coil S is taken 
from the contact points 1, 2, 3 and 4. The construction of the 
transformer coils shown in Fig. 250 indicates the primary wires 
at LL of Fig. 251. The wires of the primary coil are permanently 
attached to house wires. The reactive effect of the magnetism 




Fig. 250. — Doorbell trans- 
former. 



Fig. 251. — Details of doorbell 
transformer. 



in the coil permits only enough current to flow as will keep the 
core excited. This is a step-down transformer and the secondary 
coil contains fewer turns of wire than the primary coil. Since 
the voltage induced in the secondary coil is determined by the 
number of turns of wire in action, this coil is so arranged that 
circuits formed by attachment with different contacts give a 
variety of voltages. The numbers on the front of Fig. 250 
correspond to those of Fig. 251. The coils between contact 1 
and the others 2, 3 and 4, represent different number of turns of 
wire and in them is induced voltages corresponding with the 
number of turns of wire in each. 



350 MECHANICS OF THE HOUSEHOLD 

The Recording Wattmeter. — To determine the amount of elec- 
tricity used by consumers, each circuit is provided with some form 
of wattmeter. These meters might be more correctly called 
watt-hour meters since they register the watt-hours of electrical 
energy that pass through the circuit. 

In the common type of meter, the recording apparatus in com- 
posed of a motor and a registering dial. The motor is intended 
to rotate at a rate that is proportional to the amount of pass- 
ing current. An example of this device is the Thompson induc- 
tion meter of Fig. 252. The motion of the aluminum disc seen 
through the window in front indicates at any time the rate at 
which electricity is being used. This constitutes the rotating 
part of the motor. It is propelled by the magnetism, created by 
the passing current, and is sensitive to every 
change that takes place in the electric circuit. 
Each lamp, heater or motor that is brought 
into use or turned off produces a change of 
current in the conducting wires and this change 
is indicated by the rate of rotation of the disc. 
Fig. 252.— Record- Each rotation of the disc represents the pas- 

mg watt meter. ^ n - r»i •• i- 

sage 01 a definite amount oi electricity that is 
recorded on the registering dials. 

The shaft on which the disc is mounted is connected with the 
recording mechanism by a screw which engages with the first of a 
train of gears. These gears have, to each other, a ratio of 10 
to 1; that is, ten rotations of any right-hand gear, causes one 
rotation of the gear next to the left. The pointers on the dial 
are attached to the gear spindles. One rotation of the right- 
hand dial will move the pointer next to the left one division 
on its dial. Each dial in succession will move in like ratio. 

The meters are carefully calibrated and usually record with 
truthfulness the amount of electricity used. They are, however, . 
subject to derangement that produces incorrect registration. 

To Read the Meter. — First, note carefully the unit in which 
the dial of the meter reads. The figures above the dial circle 
indicate the value of one complete revolution of the pointer in 
that circle. Therefore, each division indicates one-tenth of the 
amount marked above or below the circle. 

Second J in reading, note the direction of rotation of the pointers. 




ELECTRICITY 351 

Commencing at the right, the first pointer rotates in the direction 
of the hands of a clock (clockwise) ; the second rotates counter- 
clockwise; the third, clockwise; etc./ alternately. The direction 
of rotation of any one pointer may easily be determined by 
noting the direction of the sequence of figures placed around 
each division. The arrows (shown above) indicate the direction 
of rotation of the pointers when the meter is in operation. 

Third, read the figures indicated by the pointers from right 
to left, setting down the figures as they are read, i.e., in a position 
relative to the position of the pointers. Note : One revolution of 
the first or right-hand pointer makes one-tenth of a revolution of 
the pointer next to it on the left. One revolution of this second 
pointer makes one-tenth of a revolution of the pointer next to it 
on the left, etc. Therefore, if, when reading the dial, it is found 
that the second pointer rests very nearly over one of the tenth 
divisions and it is doubtful as to 
whether it has passed that mark, 
it is only necessary to refer to the 
pointer next to it on the right. 
If this pointer on the right has 
not completed its revolution, it 

1. XT. X XT. J • X I. Fig. 253a.— This dial reads 9484 

shows that the second pomter has kilowatt hours. 

not yet reached the division in 

question. If it has completed its revolution, that is, passed the 

zero, it indicates that the second pointer has reached the division 

and the figure corresponding is to be set down for the reading. 

The foregoing also applies to the remaining pointers. When 
it is desired to know whether a pointer has passed a tenth di- 
vision mark, it is necessary to refer only to the next pointer 
to the right of it. 

Fourth, see if the register is direct-reading, i.e., has no multi- 
plying constant. Some registers are not direct-reading in that 
they require multiplying the dial reading by a constant such 
as 10 or 100 in order to obtain the true reading. If the register 
bears some notation such as ^^ Multiply by 100,^' the reading 
as indicated by the pointers should be multiplied by 10 or 100 
as the case may be to determine the true amount of energy 
consumed. 

Some of the earUer forms of meters were equipped with what 



/ 








10,000 


LOOO 


100 


10 




f^®' J 


\3 ^ 7 J 






KILOWATT HOURS 




V 









352 



MECHANICS OF THE HOUSEHOLD 



is known as a ^^ non-direct-reading register/' In this case, the 
reading must be multipUed by the figure appearing on the dial 
as just explained, but the dial differs from those just described 
in that the multiplying constant is generally a fraction such as 
3-^, etc., and the dial has five pointers. This older style of 
register reads in ^^watt-hours'' of ^^kilowatt-hours." 

Fifth, the reading of the dial does not necessarily show the 
watt-hours used during the past month. In other words, the 
pointers do not always start from zero. To determine the num- 
ber of watt-hours used during a certain period it is necessary to 
read the dial at the begining of a period and again at the end 
of that period. By subtracting the first reading from the second, 
the number of watt-hours or kilowatt-hours used during the 
period is obtained. 

The meter man, having in his possession a record of the 
readings of each customer's meter for the preceding months, is 
thus able to determine the amount of energy consumed monthly. 

EXAMPLES OF METER READINGS 

Fig. 2o3a shows an example of an ordinary dial reading. 
Commencing at the first right-hand pointer, Fig. 253c, it is 




Fig. 2536. — This dial reads 997 
kilowatt hours. 



10.000 1.000 100 


10 


/l 

[2 
13 
\4 


® 7JL7 ^ 313^=' 7J 
5 6/\654/\456/ 




^ 


KILOWATT HOURS 


^-^ 


Fig. 


253c.— This dial reads 9121 
kilowatt hours. 



noted that the last figure passed over by the pointer is 1. 
The next circle to the left shows the figure last passed to be 
2, bearing in mind that the direction of the rotation of this 
pointer is counter-clockwise. The last figure passed by the next 
pointer to the left is 1, while that passed by the last pointer to 
the left is obviously 9. The reading to be set down, therefore, 
is 9121. 

In a similar manner the dial shown in Fig. 2536 may be 
read. In this case, however, three of the pointers rest nearly 



ELECTRICITY 353 

over the divisions and care must be used to follow the direction 
to avoid error. Commencing at the right, the first pointer indi- 
cates 7. The second pointer has passed 9 and is approaching 0. 
The third pointer appears to rest directly over 0, but since the 
second pointer reads but 9, the third cannot have completed its 
revolution and hence the figure last passed is set down which 
in this case is 9. Similarly, the fourth or left-hand pointer 
appears to rest directly over 1 but by referring to the pointer 
next to it on the right, we find that its indication is 9 as just 
explained. Therefore, the fourth pointer cannot have reached 
1, and so the figure last passed which is is set down, which in 
this case is 9. Similarly, the fourth or left-hand pointer appears 
to rest directly over 1, but by referring to the pointer next to 
it on the right we find that its indication is 9 as just explained. 
Therefore, the fourth pointer cannot have reached 1, and so 
we set down the figure last passed which is 0. The figures as 
they have been set down, therefore, are 0997, which indicates 
that 997 kilowatt-hours of electricity have been used. 

If, for example, the reading of this meter for the preceding 
month was 976 kilowatt-hours,' the number of kilowatt-hours 
used during that month would be 997 — 976 = 21 kilowatt- 
hours. 

State Regulation of Meter Service. — Electric wattmeters are 
subject to errors that may cause them to run either fast or slow. 
Complaints made of inaccurate records or readings are usually 
rectified by the electric company. In many States all public 
utilities are governed by laws that are formulated by public 
utilities commissions or other bodies from which may be obtained 
bulletins fully describing the conditions required of public service 
corporations or owners of public utilities. The following quota- 
tion from Bulletin No. V., 233 of the Railroad Commission of 
Wisconsin, will give an illustration of the requirement in that 
State. 

Rule 14. — Creeping Meters. — No electric meter which registers upon 
"no load" shall be placed in service or allowed to remain in service. 

This means that when no electricity is being used in the sys- 
tem the motor disc should remain stationary and if it shows any 
motion under such condition it is not recording accurately. 

23 



354 MECHANICS OF THE HOUSEHOLD 

PERIODIC TESTS 

Rule 17. — Each watt-hour meter shall be tested according to the fol- 
lowing schedule and adjusted whenever it is found to be in error more than 
1 per cent., the tests both before and after adjustment being made at 
approximately three-quarters and one-tenth of the rated capacity of the 
meter. Meters operated at low power-factor shall also be tested at ap- 
proximately the minimum power-factor under which they will be required 
to operate. The tests shall be made by comparing the meter, while con- 
nected in its permanent position, on the consumer's premises with approved, 
suitable standards, making at least two test runs at each load, of at least 
30 seconds each, which agree within 1 per cent. 

Single-phase, induction-type meters having current capacities not ex- 
ceeding 50 amperes shall be tested at least once every 4 months and as much 
oftener as the results obtained shall warrant. 

All single-phase induction-type meters having current capacities exceed- 
ing 50 amperes and all polyphase and commutator-type meters having vol- 
tage ratings not exceeding 250 volts and current capacities not exceeding 
50 amperes shall be tested at least once every 12 months. 

All other watt-hour meters shall be tested at least once every 6 months. 

Rule 20. — Request Tests. — Each utility furnishing metered electric 
service shall make a test of the accuracy of any electricity meter upon 
request of the consumer, provided the consumer does not request such 
test more frequently than once in 6 months. A report giving the results 
of each request test shall be made to the consumer and the complete, 
original record kept on file in the office of the utility. 

Electric Batteries.^ — Electric batteries are composed of elec- 
tric cells that are made in two general types: the primary cell, 
in which electricity is generated by the decomposition of zinc; 
and the secondary cell or storage cell in which electricity from a 
dynamo may be accumulated and thus stored. Electric cells are 
the elements of which electric batteries are made; a single elec- 
tric cell is often called a battery but the battery is really two 
or more cells combined to produce effects that cannot be attained 
by a single element. 

Both primary and secondary batteries form a part of the house- 
hold equipment but the work of the secondary battery is used 
more particularly for electric lighting, the operation of small 
motors and for other purposes where continuous current is re- 
quired. It will, therefore, be considered in another place. 

Primary batteries are used to operate call-bells, table pushes, 
buzzers, night latches and various other forms of electric alarms 
besides which they are used in gas Ughters, thermostat motors 



ELECTRICITY 



355 



and for many special forms, all of which form an important part 
in the affairs of everyday life. Primary battery cells for house- 
hold use are made to be used in the wet and dry form, but the 
dry cell is now more extensively used than any other kind and 
for most purposes has supplanted the wet form. 

Formerly all primary cells were made of zinc and copper plates 
placed in a solution called an electrolite, that dissolved the zinc 
and thus generated electricity, the electrolite acting as a con- 
ductor of the electricity to the opposite plate. In later elec- 
tric cells the copper was replaced by plates of carbon and from 
the zinc and carbon cell was finally evolved the present-day 





Fig. 254.— Elec- 
tric dry cell. 



Carbon and 

Salammoniac 

Paste 



Fig. 255. — Details of electric 
dry cell. 



dry cell. When the use of electric cells reached a point where 
portable batteries were required, a form was demanded from 
which the solution could not be lost accidentally. The first 
electric cells in which the electrolite was not fluid was, therefore, 
called a dry cell. These cells are not completely dry. The 
electrolite is made in the form of a paste that acts in the same 
manner as the fluid electrolite and is only dry in that it is not fluid. 
In construction the dry cell is shown in Figs. 254 and 255, 
the former showing its exterior and the latter exposing its in- 
ternal construction. The container is a xinc can which is Hned 
with porous paper to prevent the filler from coming into contact 
with the zinc. The zinc further is the active electrode, the 



356 MECHANICS OF THE HOUSEHOLD 

chemical destruction of which generates the electricity. The 
parts enclosed in the container are: a carbon rod, which acts 
as the positive pole; and the filler, composed of finely divided 
carbon mixed with manganese dioxide and wet with a solution 
of salammoniac. The composition plug, made of coal-tar prod- 
ucts and rosin, is intended to keep the contents of the can in 
place and prevent the evaporation of the moisture. Binding 
posts attached to the carbon rod and soldered to the can furnish 
the + and — poles. 

In the action of cell, the salammoniac attacks the zinc in 
which chemical action electricity is evolved. The electricity is 
conducted to the carbon pole through the carbon and the salam- 
moniac solution which in this case is the electrolite. In the 
dissolution of the zinc, hydrogen gas is liberated which adds to 
the resistance of the cell and thus reduces the current. The 
presence of the hydrogen is increased when the action of the cell 
is rapid and the decrease in current is said to be due to polari- 
zation. The manganese dioxide is mixed with the filler in order 
that the free hydrogen may combine with the oxide and thus 
reduce the resistance. This process is known as depolarization. 
The combination between the hydrogen and the oxide is slow 
and for this reason the depolarization of batteries sometimes 
require severals hours. Dry cells are usually contained in paper 
cartons to prevent the surfaces from coming into contact and 
thus destroying their electrical action. 

The best cell is that which gives the greatest amount of cur- 
rent for the longest time. Under any condition the working 
value of a cell is determined by the number of amperes of current 
it can furnish. The current is measured by a battery tester 
such as Fig. 257. The + connection of the tester is placed in 
contact with the + pole of the cell or battery and the other con- 
nection placed on the — pole. The pointer will immediately 
indicate the current given out by the battery. A new dry cell 
will give 20 or more amperes of current for a short time but if 
used continuously the quantity of current will be reduced by 
polarizing until but a very small amount is generated. A cell 
that indicates less than 5 amperes should be replaced. If short- 
circuited, that is if the poles are connected without any interven- 
ing resistance, a large amount of current will be given but the 



ELECTRICITY 357 

cell will soon wear out and possibly be ruined. A cell should, 
therefore, never be allowed to become short-circuited. The vol- 
tage of a cell is practically continuous and should be from 1.5 
to 1 volt. It is quite possible that a cell may possess its normal 
voltage and yet deliver little current; the voltage of a cell does 
not indicate its working property. In order to be assured of 
active cells they should be tested at the time of purchase with 
an ammeter. 

The moisture in the paste of a cell is that which forms the 
circuit between the zinc and the carbon elements. If the paste 
has dried out its resistance is increased and the cell generates 
little current. The voltage of such a cell may be normal while 
the amperage is very low. Cells in this condition may be revived 
by adding moisture to the paste as a temporary remedy. This 
may be accomplished by puncturing the can with a nail and add- 
ing water. A solution of salammoniac may be used instead of 
water and the cell soaked to accomplish the same purpose; this, 
however, is only a temporary expedient. 

Temperature influences the working properties of an electric 
cell in pronounced manner. The moisture contained in the cell 
is composed of ammonium chloride and zinc chloride and con- 
sequently the resistance of the cell increases with the fall of tem- 
perature; the effect of the resistance thus added is a decrease in 
the flow of current. Batteries should be kept in a temperature 
as nearly as possible that of 70°F. The battery regains its 
normal rate of discharge when the temperature is restored. 

The normal voltage and amperage for a given make of cell is 
practically the same for all. The size of the cell does not in 
any way influence the voltage. Small cells and large cells are 
the same. The large cells are advantageous only in that they 
give out a greater number of ampere-hours of energy. All bat- 
teries are rated in the number of ampere-hours of current they 
are capable of furnishing. The amper-hour represents an 
ampere of current for one hour. On this basis all batteries are 
rated for the total amount of energy they are capable of pro- 
ducing. If the battery is worked at a high current, its life is 
short; if however, it is discharged at a low rate, its life should be 
long. In all cases the product of the number of amperes and 
the number of hours constitute the ampere-hours of energy 
produced. 



358 



MECHANICS OF THE HOUSEHOLD 




Series - 6 Volts 

a 




Multiple - IH Volts 
h 




Series -Multiple - 6 Volts 
C 




Series -Multiple 
d 



6 Volts 



D 




E 



Series -Multiple - 6 Volts 



Fig. 256. — Battery combinations. 



Battery Formation. — For 
ordinary household work as 
that of operating doorbells, 
etc., the cells which form a 
battery are joined in series, 
that is the positive or car- 
bon pole of one cell is joined 
to the zinc or negative pole 
of the next. The cells so 
connected are placed in cir- 
cuit with the bell and push 
button. If by accident the 
two cells of a battery are 
joined with both carbon 
poles or both zinc poles to- 
gether the battery will give 
out no current because the 
voltage is opposed. 

In the use of batteries for 
ignition as for gasoline en- 
gines, automobiles, etc., the 
arrangement of the cells has 
frequently a decided in- 
fluence on the effect pro- 
duced. In Fig. 256 A is 
represented four cells joined 
in series, that is the carbon 
or + poles are joined with 
the zinc or — poles, alter- 
nately. Connected in this 
manner if each cell gives 1.5 
volts the battery will give 
4 X 1.5 = 6 volts; the cur- 
rent, however, will remain 
as that of a single cell. If 
the cells singly give 20 volts, 
the battery will give 20 volts. 
When cells are connected in 
this form the current passes 



ELECTRICITY 359 

through each cell in turn and is as much a part of the circuit 
as the wires. Should one of the cells be ''dead'' — that is de- 
livering no current — it will act as additional resistance and the 
current is reduced. 

When joined in multiple or parallel connection as in Fig. 256 B, 
in which all similar binding posts are connected, the effect is 
decidedly different. In the multiple connection all of the zincs 
are joined to act as a single zinc and all of the carbons are like- 
wise joined and act as a single carbon. In such a combination 
the voltage will be that of a single cell 1.5 volts, but the amper- 
age will be four times that of a single cell or 80 amperes. 

The diagrams and following descriptions of possible combina- 
tions were taken from a bulletin on battery connections issued 
by the French Battery and Carbon Co. 

By combining the series and multiple connections, as shown in 
Fig. C, both the voltage and current can be increased over that 
delivered by one cell. Referring to the figure, it is seen that 
in each of the two rows of four cells the cells are connected 
in series. This would produce 6 volts and 20 amperes for the 
series of four which may now be assumed as a unit, so that 
the two rows can be imagined as two large cells, each of 
which has a normal output of 20 amperes at 6 volts. Now 
by connecting the similar poles of two such large cells they 
are in multiple and we get an increased current or 40 amperes 
and 6 volts, which is the capacity of the eight cells connected 
as shown in the figure. This is commonly designated as a 
multiple-series battery. 

Fig. 256 D illustrates a multiple-series connection made in a 
different manner, but which produces the same voltage and 
current as the above mentioned. In Fig. D, two cells at a time 
are connected in multiple, and these sets are then connected in 
series. The capacity of each set of two is 40 amperes at 13-^ volts, 
and as these four sets are connected in series the total output of 
the eight cells combined fe 6 volts and 40 amperes, the same as 
that produced by the connections shown in Fig. C. 

Fig. E shows the multiple-series connection illustrated in Fig. 
Z>, applied to twelve cells in which four sets of three cells each 
are wired in series, the three cells of a set being in multiple so that 
the capacity of a set is 13^^ volts and 60 amperes. By connecting 



360 MECHANICS OF THE HOUSEHOLD 

the four sets in series as shown, the total capacity will be 60 
amperes at 6 volts. 

The use of the series-multiple connection is a distinct step 
forward in dry-cell use. The arrangement of cells shown in Figs. 
C or D is better than the arrangement in Fig. A^ in just the same 
way that a team of horses is better than a single horse. One 
horse pulling a load of 2 tons may become exhausted in one hour, 
but two horses pulling that same load may work continuously 
for six hours. It is true that in Fig. C there are twice as many 
cells used as in Fig. A, but the eight cells in Fig. C will do from 
three to four times as much work as the four cells in Fig. A, In 
other words, while more cells are used in the multiple-series 
arrangement, the amount of service per cell is greater and the 
service is, therefore, cheaper in the multiple-series arrangement. 

Some battery manufacturers sell their batteries put up in boxes, 
the cells being connected up in multiple-series and surrounded 
by pitch or tar to keep out the moisture. This has certain 
advantages as well as certain disadvantages. One of the objec- 
tions to this method of putting up dry cells is that if by any 
chance one cell out of the eight or twelve which are buried in the 
pitch is defective it will run all of the cells down, and being 
buried offers no means of detection or removal. It is not pos- 
sible to guarantee absolutely that a weak cell will not be occa- 
sionally included in a large number, so dry cells may be expected 
to vary to some degree among themselves. 

It is interesting to know the effect of one weak cell on a series- 
multiple arrangement. If, for example, in Fig. C or Fig. D, 
the dotted line connecting (a) and ih) be used to indicate a cell 
which is partly short-circuited by internal weakness or external 
defect the result is as follows : 

In the arrangement shown in Fig. C, where one cell of the 
upper four is short-circuited, the lower four will discharge through 
the upper four even though the external circuit is not closed; 
that is, one short-circuited cell will cause a run-down in all of the 
cells. In Fig. D, however, one short-circuited cell will influence 
not the entire set but the other one to which it is directly con- 
nected. There is thus seen to be an advantage in the arrange- 
ment of Fig. D and Fig. £', over the arrangement in Fig. C, 

In making connections between cells insulated wire should be 



ELECTRICITY 361 

used, or special battery connectors are preferably employed. 
The ends of the wires or connectors and the binding posts must 
be scraped clean so that good electrical connection can be made 
between the two, and the knurled nuts should be screwed tight 
into place. Care must also be taken that the pasteboard covering 
around the battery is not torn. This would allow contact be- 
tween the zinc containers, and thus short-circuit the cells. The 
batteries should be placed so that the zinc cans and the binding 
posts of any cell do not come into contact with any other cell. 
Vibration might cause enough motion for the brass terminal to 
wear through the pasteboard of the neighboring cell and make 
contact with the zinc can. 

Different classes of work require different amounts of current 
at different voltages and by choosing the proper combination of 
series, multiple, or series-multiple connec- 
tions practically every requirement can be 
fulfilled. For electric bells, telegraph instru- 
ments, miniature lights, toy motors with fine 
wire windings, etc., series connection is recom- 
mended for the reason that the resistance of 
the external circuit is high and a large volt- 
age is necessary. For spark coils, magnets 
and toy motors with large wire windings, mul- 
tiple or series-multiple connection of batteries ^^^- 257.— Battery 

tester. 

should be used as a high voltage is not required. 

For some work, gas-engine ignition especially, it is economical 
to have two complete sets of batteries, either of which can be 
thrown into the circuit at will, so that while one set is delivering 
current the other is recuperating. It has been estimated that 
by using two sets of batteries, properly connected to give the 
desired current, the life of each set is increased about four times. 
Thus it is seen that a saving of 50 per cent, is effected in the cost 
of the batteries. 

Battery Testers. — The ^^ strength'^ of a cell is determined by 
the amperes of current it is capable of producing; therefore, a 
meter that will indicate the amount of current being produced 
is used to test the (airrent strc^ngth of the cell. Battery testers 
are made to indicate voltage or amperage and sometimes the 
instrument is made to indicate both volts and amperes. As ex- 




362 



MECHANICS OF THE HOUSEHOLD 



plained above, the voltage of a cell is not a true indicator of its 
strength. The ampere meter or ammeter, as it is termed, is the 
proper indicator of the strength of the cell. 

The common battery tester does not always give the exact 
number of amperes of current, but it indicates the relative 
strength which is really the thing desired. When the current 
from an active cell is once shown on the dial of the tester, any 
other cell of the same intensity will be indicated in like amount. 

Electric Conductors. — Covered wire for carrying electricity 
is made in a great variety of forms and designated by names that 
have been suggested by their use. These wires are made of a 
single strand or in cables, where several wires are collected, 
insulated and formed into a single piece. Cables may contain 
any number of insulated wires. 

The sizes of wires are determined by a wire gage. In the 
United States the B. & S. gage is used as the standard for all 
wires and sheet metal. The gage originated with the Brown & 
Sharp Mfg. Co. of Providence, R. I., and has become a national 
standard by common consent. The numbers range from No. 
0000 to No. 60. The size of wire for household electrical service 
ranges from No. 18 which is 0.04 inch in diameter to No. 8 
which is 0.128 inch across. The carrying capacities in amperes 
of wires, as given by the Underwriters' table of sizes from No. 8 
to No. 18, are as follows: 



Wire 
gage 

No. 


Rubber 

insulation, 

amperes 


other 

insulation, 

amperes 


Wire 


Rubber 

insulation, 

amperes 


other 

insulation, 

amperes 


8 


35 


50 


14 


15 


20 


10 


25 


30 


16 


6 


10 


12 


20 


25 


18 


3 


5 



Lamp Cord. — The flexible cord used for drop lights, connectors, 
portable lamps, extensions, etc., is made of two cords twisted to- 
gether or two cords laid parallel and covered with braided silk or 
cotton. The conductors consist of a number of No. 30 B. & S. 
gage, unannealed copper wires twisted into a cable of required 
capacity. The conductor is wound with fine cotton thread over 
which is a layer of seamless rubber, and the whole is covered with 



ELECTRICITY 363 

braided cotton or silk. Lamp cord is sold in three grades, old 
code, new code, and commercial, which vary only in the thickness 
and quality of rubber which encloses the conductor. 

The new code lamp cord is identical with the old code form 
except that it is required by the National Board of Fire Under- 
writers to be covered with a higher quality of rubber insulation 
than was used in the old form. The commercial cord is not 
recognized by the National Board of Underwriters. It is practic- 
ally the same as that described but does not conform to the tests 
prescribed for the new code cord. 

The sizes of the conductors enclosed in the lamp cord are made 
equal in carrying capacity to the standard wire gage numbers. 
The sizes ordinarily used are No. 18 and 20 gage but they are 
made in sizes from No. 10 to No. 22 of the Brown & Sharp gage. 

Portable Cord. — This is a term used to designate reinforced 
lamp cord. The wires are laid parallel and are covered as with 
a supplementary insulation of rubber. The additional insulation 
and the braided covering assumes a cylindrical form. The 
covering is saturated with weatherproof compound, waxed and 
polished. 

Annunciator Wire. — This wire is made in the usual sizes and 
covered with two layers of cotton thread saturated with a special 
wax and highly polished. As the name implies it is used for an- 
nunciators, door bells and other purposes of like importance. 

Private Electric Generating Plants. — The conveniences to be 
derived from the use of electricity were for many years available 
only by those who lived in distributing areas covered by commer- 
cial electrical generating plants. Except in towns of sufficient 
size to warrant the erection of expensive light and power systems 
or along the lines of electric power transpiission, current for 
domestic purposes was not obtainable. 

Within a comparatively few years there have been developed 
a number of small electric generating systems that are suitable 
for supplying the average household with the electric energy for 
all domestic conveniences. The combination of the gasoline en- 
gine, the electric dynamo and the storage battery have made pos- 
sible generating apparatus that is operated with the minimum of 
difficulty and which supplies all of the electric appliances that 
were formerly served only from commercial electric circuits. 



364 MECHANICS OF THE HOUSEHOLD 

An electric generating system is commonly termed an electric 
plant. It consists of an engine for the development of power, 
a dynamo for changing the power into electricity and — to be of 
the greatest service — a storage battery for the accumulation of 
a supply of energy to be used at such times as are not convenient 
to keep the dynamo in active operation. 

Such a combination, each part comprised of mechanism with 
which the average householder is unfamiliar, seems at first too 
great a complication to put into successful practice. Such, how- 
ever, is not the case. The operation of small electric generating 
plants is no longer an experiment. Their general use testifies to 
their successful service. The working principles are in most cases 
those of elementary physics combined with mechanism, the 
management of which is not difficult to comprehend. Such 
plants are made to suit every condition of application and at a 
cost that is condusive to general employment. 

In a brief space it is not possible to enter into a detailed discus- 
sion of the gasoline engine, the electric dynamo, and the storage 
battery with the various appliances necessary for their operation; 
it is, therefore, intended to give only a general description of the 
leading features of each. The manufacturers of such plants 
furnish to their customers and to others who are interested de- 
tailed information with explicit instructions for their successful 
management. 

The first private lighting plants were made up of parts built 
by different manufacturers and assembled to form generating 
systems with little regard to their adaptability. A gasoline 
engine belted to a dynamo of the proper generating capacity sup- 
plied the electricity. Neither the engines nor the dynamos were 
particularly suited to the work to be performed, yet these com- 
binations were sufficiently successful to command a ready sale. 
The energy thus generated was accumulated in a storage battery 
from which was taken the current for a lighting and heating de- 
vice. Besides the generating and storage apparatus there is 
required in such a system, a switchboard, to which are attached 
the necessary meters and switches that are required to measure 
and direct the current to the various electric circuits. 

Foresighted manufacturers, comprehending the probable future 
demand, began the construction of the various parts, suited to 



ELECTRICITY 



365 



the work and the conditions under which they were to be em- 
ployed. The manufacture of apparatus, designed for the special 
service and composed of the fewest possible parts, has reduced 
the operating difl&culty to a point of relative simplicity. Ex- 
perience in the use of a large number of these plants has revealed 
to the maker the course of many minor difficulties of operation 
and the means of their correction. The mechanism has been 
improved to prevent possible derangement and to simplify the 




Fig. 258. — Household electric generating plant. 

means of control, until the private electric plant is successfully 
employed by those who have had no former experience with 
power-generating machines. 

As an example of the private electric plant Fig. 258 shows 
the apparatus included in a combined engine, dynamo and switch- 
board,' connected with a storage battery. The relative size of 
the machine is shown by comparison with the girl in the act of 
starting the motor. This plant is of capacity suitable for sup- 
plying an average home with electricity for all ordinary domes- 
tic uses. A nearer view of the generating apparatus is given 
in Fig. 259 in which all of the exterior parts are named. An 



366 



MECHANICS OF THE HOUSEHOLD 



interior view of the generating apparatus is given in Fig. 260, 
in which is exposed all of the working parts. The right-hand 
side of the picture shows all of the parts of the gasoline engine 
that furnishes the power for driving the generator. This is an 
example of an air-cooled gasoline engine in which the excess heat 
developed in the cyHnder is carried away by a drought of air. 
The air draft is induced by the flywheel of the engine, which is 
constructed as a fan. The blades of the fan, when in motion, are 





M 


H 


[ 


J^^'PSHQ SWITCH 
Pjy'Nr VAtVF 


r. ' ■ A^& 


^H 


Hi 






III 


-^ 




i 






J 


gnn 


■H 


L -=-'- 


liii:;: 


'^H 


^^^H 


^^^^H 


i 


^ 


■ 


1 


P 


u'l I 



Fig. 259. — Combined motor, electric generator and switchboard. 

SO set as to draw air into the top of the engine casing and ex- 
haust it from the rim of the wheel. The air in passing takes up 
the heat in excess of that necessary for the proper cylinder tem- 
perature. This form of cylinder cooling takes the place of the 
customary water circulation and thus eliminates its attending 
sources of trouble. In principle the engine is the same as is 
employed in automobiles and other power generation. 

On the left-hand side is seen the dynamo and switchboard. 



ELECTRICITY 



367 



The dynamo armature is attached to the crankshaft of the engine 
by which it is rotated in a magnetic field to produce the desired 
amount of electricity. The brushes, in contact with the com- 
mutator, conduct the electricity as it is generated in the armature, 
which after passing through the switchboard is made available 
from the two wires at the top of the board marked ^'Hght and 
power wires/' These wires are connected with the storage bat- 
tery and also to the house circuits through which the current is 
to be sent. 




■iiiiiiiii 


E 


lliiii|iiii 


iiiiiiiiiiiii 


%, -; 

%. 


Wiliiiii 


^ 


liiiiiiiiiiH ^ 
liiBiiiiiiiiii 



Fig. 260. — Details of motor, electric generator and switchboard. 



Referring to the switchboard of Fig. 259, the three switches 
and the ammeter comprise the necessary accessories. The start- 
ing switch is so arranged that by pressing the lever a current of 
electricity from the storage battery is sent through the dynamo. 
The dynamo acting as a motor starts the engine. When the 
engine has attained its proper speed its function as a dynamo 
overcomes the current pressure from the battery and sends elec- 
tricity into the cells to restore the expended energy, or if so de- 
sired the current may be used directly from the dynamo for any 



368 MECHANICS OF THE HOUSEHOLD 

household purpose. The box enclosing the switch contains a 
magnetic circuit-breaker so constructed that when the battery is 
completely charged the switch automatically releases its contact 
and stops the engine. 

The ^'stopping switch'' at the right of the board and the 
^^ switch for hght and circuit'' on the left are used respectively 
for stopping the engine and for opening and closing the house 
circuits. 

The meter performs a multiple function, in that it shows at 
any time the condition of charge in the storage battery, the rate 
at which current is entering or leaving the battery and also acts 
to stop the engine when the battery is charged. At any time the 
pointer reaches the mark indicated in the picture, the ignition 
circuit is automatically broken and the engine stops. The fuses 
on the board in this case perform the same function as those al- 
ready described. 

Storage Batteries. — These batteries have already been men- 
tioned as secondary batteries. They are sometimes called elec- 
tric accumulators. The electricity is stored or accumulated, not 
by reason of the destruction of an electrode as in the primary 
cell but by the chemical change that takes place in the plates as 
the charging current is sent through the cell. When the battery 
is discharged, the current from the dynamo is sent through the 
battery circuit in the reverse direction to that of the discharge 
and the plates are restored to their original condition. The 
action that takes place in charging and discharging is due to 
chemical changes that take place in the plates and also in the 
solution or electrolyte in which the plates are immersed. 

There are two types of storage batteries, those made of lead 
plates immersed in an acid electrolyte and the Edison battery 
which is composed of iron-nickel cells immersed in a caustic 
potash electrolyte. The former type is most commonly used 
and is the one to be described. 

The lead-plate cell illustrated in Fig. 262 shows all of the 
parts of a working element. The plates are made in the form 
of lead grids which when filled to suit the requirements of their 
action, form the positive and negative electrode's. The negative 
plates are filled with finely divided metallic lead which when 
charged are slate gray in color. The positive plates are filled 



ELECTRICITY 



369 



with lead oxide. When charged they are chocolate brown in 
color. In the figure there are three positive and four negative 
plates which together form the element, then with their sepa- 
rators are placed in a solution of sulphuric acid electrolyte. The 
separators are thin pieces of wood and perforated rubber plates 
that keep the positive and negative plates from touching each 
other and keep in place the disintegration produced by the 
electro-chemical action of the cell. 

The unit of electric capacity in batteries is the ampere-hour. 
The cell illustrated will accumulate 80 ampere-hours of energy. 
It will discharge an ampere of current for 80 
hours. If desired it may be discharged at the 
rate of two amperes for 40 hours, or four amperes 
for 20 hours, or at any other rate of amperes and 
hours, the product of which is 80. The number 
of ampere-hours a cell will accumulate will depend 
on the area of the positive and negative plates; 
large cells will store a greater number of ampere- 
hours than those of small size. 

The cells, no matter what size, give an aver- 
age electric pressure of 2 volts. 

The plates are joined by heavy plate-straps 
connecting all of the positives on one end and 
all of the negative kind on the opposite end. To 
insure rigidity the two sets are secured to the rub- 
ber cover by locknuts. In this cell the plates are 
suspended from the cover. The plate terminals Fig. 2 6 1 . — 
are made of heavy lead connectors that when testing"^^ storage 
formed into a battery are joined together with battery electro- 
lead bolts and nuts. ^ ^* 

The electrolyte is a solution of pure sulphuric acid in distilled 
water and on its purity depends, in a great measure, its action 
and length of life. The electrolyte is made of a definite density 
which is expressed as its specific gravity. When fully charged 
the electrolyte will test 1220 by the hydrometer. That is, it 
will be 1.220 heavier than water. When discharged it will test 
by the hydrometer 1185. This means that in discharging the 
density has been reduced to 1.185 that of water. The chemical 
change in the electrolyte is, therefore, an important part of the 

24 




370 MECHANICS OF THE HOUSEHOLD 

charge and discharge of the cell. The density of an electrolyte 
may be determined by a hydrometer such as Fig. 261. This is an 
ordinary glass hydrometer such as is used for determining the 
density of fluids, enclosed in a glass tube, to which is attached 
a rubber bulb. The point of the tube is inserted into the open- 
ing at the top of the cell and the electrolyte drawn into the tube 
by the reopening of the collapsed bulb. The density is then read 
from the stem of the hydrometer. 

The Pilot Cell. — In order to make apparent this density of 
the electrolyte without the necessity of its measurement with a 
hydrometer, one cell of the battery is provided with a gage as 
that of Fig. 262. This is an enlargement of the end of the jar 
in which floats a hollow glass ball of such weight that it will at 
any time indicate by its position the relative density of the 
solution. When the cell is charged the ball stands at the top 
of the gage and indicates a density 1220; when discharged it is 
at the bottom and expressed by its position a density of 1185. 
The electrolyte densities are the indicators of the conditions of 
charge. The ball by its position shows at a glance the quantity 
of electricity in the battery. 

The voltage usually employed in household electric plants is 
that of a battery composed of 16 cells. Since the normal voltage 
of a storage cell is 2 volts such a battery joined in series is 32 
volts. This voltage for the purpose fulfills all ordinary condi- 
tions and is generally employed. A battery of 16 cells, of 
80-ampere-hour capacity, will deliver current of 1 ampere for 
80 hours at 32 volts intensity. A 20-watt lamp on a 32-volt 
circuit requires % ampere for its operation. The battery will, 
therefore, keep lighted one such lamp for 96 hours, or four 20- 
watt lamps may be lighted continuously for 24 hours, or eight 
lamps for 12 hours, before recharging. 

Aside from its ability to supply the required light for the 
average home, it furnishes energy sufficient for heating a flat- 
iron or other heating apparatus, to operate motors for pumping 
water, driving a washing machine or any other of the domestic 
requirements. 

Such plants are made in sizes to suit any condition of require- 
ment. In large establishments a larger motor generator and 
battery will be necessary with which to generate and store the 



ELECTRICITY 



371 



required electricity but in any case suitable apparatus is to be 
obtained to meet any requirement of light, heat or power 
developed. 



BOLT 
CONNECTOR- 



POSITIVE 
TERMJNAU^ 



NEGATIVE 
TERMINAL 



SEMI-HARD 
RUBBER COVER 




WOOb 
SEPARATOR 



IHEGATNl 
PLATE 

'^PLATE 
SUPPORT LOCK 

'-POSmVE PLATE 

M^PERFORATED HARD 
"^^ RUBBER SEPARATOR 

Fig. 262. — Electric storage cell. 

National Electrical Code. — The details governing the size, the 
manner of placing and securing wires in buildings is included in 
the regulations published by the National Board of Fire Under- 
writers as the National Electric Code. Likewise the mechanical 
construction of all apparatus dealing with electric distribution 
is definitely specified so that manufacturers furnish reliable 
materials for all requirements. In the specifications for furnish- 



372 MECHANICS OF THE HOUSEHOLD 

ing buildings with the use of electricity, descriptions are made 
of the desired types and styles of the switches and various other 
fixtures to suit the requirements. 

Electric Light Wiring. — In the equipment of a house for the 
use of electricity, the wiring, together with distributing panel, 
the various outlets, receptacles, switches, and other appliances 
that make up the system, is of more than passing consequence. 
In the construction of the electric system it is important that the 
wires and their installation be done in a manner to meet every 
contingency. 

The following descriptions for electric house wiring were taken 
from a set of specifications published by the Bryant Electric Co. 
as applying to buildings of wood frame construction. The speci- 
fications serve as explanations for the appliances required in an 
ordinary dwelling. The specifications are for the least expensive 
form of good practice in wiring for frame buildings. They would 
not be permitted in large cities where further protection from fire 
is required and where more rigid rules are demanded by the 
Board of Fire Underwriters. 

1. System. — The circuit wiring shall be installed as a two- wire direct 
current or alternating system. Not more than 16 outlets or a maximum of 
660 watts shall be placed on any one circuit, allowing 110 watts for each 
baseboard plug connection or extension outlet and 55 watts for each 16 
candlepower lamp indicated at the various wall and ceiling outlets on plans. 
All wiring shall be installed as a concealed knob-and-tube system. 

The type of wiring is designated as a two-wire direct or alter- 
nating current system in order that there shall be no doubt as 
to the method of wiring to be used. There are other methods 
that might be employed that need not be discussed here. 

The 16 outlets mentioned are intended to cover all lamps or 
plug attachments that are to be used for heaters, fans, motors, 
or any other electric device. The 660 watts at 110 volts pres- 
sure will require 6 amperes in the main wires of the circuit, 
which is the maximum current the wires are intended to carry. 
This does not mean that 110-watt lamps might not be used 
but that no single circuit shall carry lamps that will aggregate 
more than 660 watts. 

The concealed knob-and-tube system mentioned is illustrated 
in Figs. 263 and 264, in which the wires which pass through joists 



ELECTRICITY 



373 



and studding are to be insulated by porcelain tubes and those 
wires which lay parallel to these members are to be fastened to 

porcelain knobs which are 
secured by screws to the wood 
pieces to prevent any possi- 
bility of coming into contact 
with electric conducting ma- 
terials. 




Fig. 263. — Manner of securing wires 
by the knob-and-tube system for ceiling 
outlets. 



A 



"«;• 

-&>:] 



A 



2. Outlets. — At each and every 
switch, wall, ceiling, receptacle or 
other outlet shown on plans, install 
a metal outlet box of a style most 
suitable for the purpose of the outlet. All outlet boxes must be rigidly 
secured in place by approved method and those intended for fixtures shall 
be provided with a fixture stud, or in the case of large fixtures, a hanger to 
furnish support independent of 
the outlet box. 

Outlet Boxes. — For tne 
safe and convenient accom- 
modation of switches, re- 
ceptacles or other connec- 
tions in the walls and ceilings 
of a building, outlet boxes 
are used as a means of secur- 
ing the wire terminals to the 
receptacles. These boxes 
are made in a number of 
forms for general application. 
One style is shown in Fig. 
265. The boxes are made 
of sheet steel and arranged 
to be secured in place with 
screws. The box is further 
provided with screw fasten- 
ings to which the switch or 
receptacle may be firmly 
attached. 




i^^jXji 



ffooTr 



Fig. 264. — This shows the knob-and- 
tube system of securing the wires in parti- 
tions and the manner of fastening metal 
"cut out" boxes; for switch, attachments, 
phigs, etc. 



3. Installation of Wires, Etc. — All wires shall be rigidly supported on 
porcelain insulators which separate the wire at least 1 inch from the sur- 



374 MECHANICS OF THE HOUSEHOLD 

face wired over. Wires passing through floors, studding, etc., shall be pro- 
tected with porcelain tubes, and where wires pass vertically through bottom 
plates, bridging, etc., of partitions, an extra tube shall be used to protect 
wires from plaster droppings. Wires must be supported at least every 4 
feet and where near gas or water pipes extra supports shall be used. All 
porcelain material shall be non-absorptive and broken or damaged pieces 
must be replaced. Tubes shall be of suflBcient length to bush entire length 
of hole. At outlets the wires shall be protected by flexible tubing, the same 
to be continuous from nearest wire support to inside of outlet box. Wires 
installed in masonry work shall be protected by approved rigid iron conduit 
which shall be continuous from outlet to outlet. 

The method and reasons for supporting the wires described 
above are as have already been mentioned under item 1. The 
reason for extra supports near gas pipes and water 
pipes is as a precaution against the possibility of 
short-circuiting. 




4. Conductors. — Conductors shall be continuous from 
outlet to outlet and no splices shall be made except in 
outlet boxes. No wire smaller than No. 14 B. & S. gage 
shall be used and for all circuits of 100 feet or longer, 
-p, 2A5 o't- ^^* ^^^ ■^* ^ ^' ^^^^ ^^ larger shall be used. All con- 
let box. ductors of No. 8 B. & S. gage or larger shall be stranded. 
Wires shall be of sufficient length at outlets to make con- 
nection to apparatus without straining connections. Splices shall be made 
both mechanically and electrically perfect, and the proper thickness of 
rubber and friction tape shall be then applied. 

Continuous conductors are required because of the possibility 
of defects in the joints of spliced wire. 

5. Position of Outlets. — Unless otherwise indicated or directed, plug 
receptacles shall be located just above baseboard; wall brackets, 5 feet above 
finished floor in bedrooms, and 5 feet 6 inches in all other rooms; wall 
switches, 4 feet above finished floors. All outlets shall be centered with re- 
gard to panelhng, furring, trim, etc., and any outlet which is improperly 
located on account of above conditions must be corrected at the contractor's 
expense. All outlets must be set plumb and extend to finish of wall, ceil- 
ing or floor, as the case may be, without projecting beyond same. 

6. Materials. — All materials used in carrying out these specifications 
shall be acceptable to the National Board of Fire Underwriters and to the 
local department having jurisdiction. Where the make or brand is speci- 
fied or where the expression ''equal to'^ is used, the contractor must notify 
the architect of the make or brand to be used and receive his approval before 
any of said material is installed. Where a particular brand or make is 
distinctly specified, no substitution will be permitted. 



ELECTRICITY 375 

7. Grade of Wire. — The insulation of all conductors shall be rubber, 
with protecting braids, which shall be N.E.C. Standard (National Electrical 
Code Standard). 

8. Outlet Boxes. — Outlet boxes shall be standard pressed steel, knock- 
out type and shall be enameled. 

9. Local Switches. — Local wall switches shall be two-button flush type 
completely enclosed in a box of non-breakable insulating material with 
brass beveled-edge cover plate finished to match surrounding hardware. 

Fig. 269 shows the various forms and grades of switches that 
there are on the market. The screws which attach the plate to 
the switch enter bushings that are under spring tension thereby 
preventing defacement of the plate by overtightening of the 
screws. Single-pole is to be used where the load will not be in ex- 
cess of 660 watts; double-pole to be used where the load is more 
then 660 watts or where for any other reason it is desirable to 
break the current at both wires. Three-point switches are to be 
used when a light or group of lights is to be controlled, as hall 
lights that may be lighted or extinguished, from either the top 
or at the bottom of a stairway. Four-point switches are to be 
used between and two, three-point switches to control additional 
lights. Where two or more switches are placed together an 
approved gang plate is to be provided which designates the use 
of each switch. Where indicated on the plan, clothes closets 
shall be equipped with automatic door switch to connect the light 
when the door is open. 

10. Pilot Lights. — Switches controlling cellar, attic and porch lights 
shall have pilot lamp in parallel on the load side of the switch. The switch 
in Fig. 3 requires for its installation a two-gang outlet box. The ruby bull's- 
eye which covers the lamp is practically flush, extending from the wall no 
further than the buttons of the switch. 

Pilot lights are intended to indicate the operation of other 
lights or apparatus that cannot be directly observed. 

The term bulFs-eye applies to a colored-glass button covering 
a miniature lamp which burns whenever a light is used which is 
apt to be forgotten and allowed to burn for a longer time than 
necessary. 

IL Plug Receptacles. — Plug receptacles shall be of the disappearing- 
door type, with beveled-edge brass cover plate finished to match surround- 
ing hardware (see Fig. 26G). In this receptacle the doors are pushed inward 
by the insertion of the plug and upon its withdrawal close automatically, 



376 MECHANICS OF THE HOUSEHOLD 

effectually excluding dirt and concealing the live terminals. It is the latest 
and best plug receptacle obtainable. 

Plug receptacles are the attachments for the terminal pieces 
of plugs, which temporarily connect portable lamps, electric fans 
or other devices, they are made in many forms. 

12. Wall and Ceiling Sockets. — One-light ceiling receptacles shall 
be of a type to fit standard 33-^-inch or 4-inch outlet boxes. Wall sockets 
shall be of the insulated base type. Sockets in cellars shall be made entirely 
of porcelain and of the pull type. All lamp sockets used in fulfilling these 
specifications shall have an approved rating of 660 watts, 250 volts. 

13. Drop Lights. — Drop lights shall consist of the necessary length of 
reinforced cord supported by an insulated rosette with brass base and cover; 
the latter to cover 4-inch outlet box, and furnished with a key socket com- 
plete with a 2J^-inch shade-holder. Each drop cord shall have an adjuster. 

14. Heater Switch, Pilot and Receptacle. — Heating device outlets 
shall be equipped with combination of switch, pilot light and receptacle with 
plug and spare pilot lamp. 

15. Service Switch. — The service-entrance switch shall be 30 amperes, 
porcelain base with connections for plug fuses. 

Installation of Service Switch. — Service switch shall be installed in 
a moisture-proof metal box with hinged door. 

Panel Cabinet. — The distributing panel cabinet shall be of steel not 
less than No. 12 gage reinforced with angle iron frames, which shall be se- 
curely riveted in place. Cabinet shall be larger than panel to give at least 
4-inch wire space around panel and shall be given at least two coats of mois- 
ture-repellant paint. 

Distributing Panel. — The distributing panel shall consist of two-wire 
125-volt branch cutouts, two-wire 125-volt porcelain-base panel-board 
units, two-wire 125-volt porcelain-base deadfront panel-board units. The 
distributing panel shall be surrounded with an ebony asbestos or slate 
partition 3^^ inch thick which will form a wire space around panel. 

Fuses. — All fuses for branch circuits shall be not more than 10 amperes 
capacity. The contractor shall furnish the owner with 150 per cent, of 
required number of 125-volt plug-type fuses for complete installation. 

Panel Trim and Door. — The panel trim and door shall be of steel, with 
brass cylinder lock and concealed hinges, all furnished under this contract. 
A directory of circuits and outlets served by panel shall be enclosed in glass 
with metal frame, mounted on inside of panel door. 

Hardware. — All hardware furnished under this contract shall match in 
quality and finish other adjacent hardware. 

Three-way Control. — The nearest outlet at top and bottom of all stairs 
and in entrance hall shall be controlled by three-way switches located on 
separate floors where directed. 

Electrolier Control. — Wherever there are ceiling outlets for fixtures 
having three or more sockets controlled by wall switches three wires shall 



ELECTRICITY 377 

be run between the switch box and the outlet to permit the use of electrolier 
switches. 

Dining-room Circuit. — Furnish and install in dining-room, where indi- 
cated on plans, an approved floor box containing an approved 25-ampere 
plug receptacle. The wires connecting this receptacle to the center of 
distribution shall be No. 10 B. & S. gage. Furnish and deliver to whom di- 
rected an approved multiple-connection block consisting of three individually 
fused plug receptacles. . The connection between the plug receptacle and 
this block shall be made by means of 10 feet of No. 10 B. & S. approved silk- 
covered portable cord with an approved 20-ampere cord connector 2 feet 
from the multiple block. 

House Feeders. — The size of the feeder from the service switch to the 
panel board shall be figured in accordance with the National Code rules for 
carrying capacity, allowing for all circuits being fully loaded. The feeder 
shall be of sufficient size, however, to confine the drop in voltage with all 
lights in circuit to 1 per cent, of the line voltage. 

Service Connection. — Make extension of house feeder overhead to 
lighting company's mains and make all connections complete to the satis- 
faction of the light company and the architect. Furnish and install the 
necessary frame or backboard for meter. 

Call Bells. — The contractor shall furnish, install and connect all push 
buttons, bells, buzzers and annunciators, as shown on plans or therein 
described. All wiring shall be cleated in joists, studs, etc., with insulated 
staples. Damp places, metal pipes of all descriptions, flues, etc., must be 
avoided and wire fastenings must be applied in such a way that insulation 
is not damaged. No splices shall be made where same will not be accessible 
at any time after completion of building. Wires shall not be smaller than 
No. 18 B. & S. gage and shall be damp-proof insulated. Bells, buzzers, but- 
tons, etc., shall be of approved make. Push button for main entrance door 
shall be provided with ornamental place with approved finish. Push button 
in dining-room shall consist of combination floor push, with necessary length 
of flexible cord and approved portable foot push. Furnish and install 
where directed three cells of carbon cylinder battery in a substantial cabinet. 

Burglar Alarm. — Furnish and install complete burglar alarm system 
consisting of the necessary wires, window springs, door springs, night latch 
cutout for front door, bell, batteries, cabinet, interconnection strip, etc., 
and everything required for a complete open-circuit system. Each window 
sash and door throughout the building shall be equipped with contact 
spring of approved make and all springs on same side of building on each 
floor shall be wired on one circuit and terminated on single-pole knife s^\itch 
on interconnection strip. The interconnection strip shall be located as 
directed and shall have cutout switches for each circuit as well as a double- 
pole battery switch. The battery shall consist of at least three dry cells in 
suitable cabinet placed where directed and both positive and negative leads 
shall be carried direct to interconnection strip. The burglar-alarm wires 
shall be not less than No. 16 B. & S. gage, insulated and installed as speci- 
fied for call bells. 



378 MECHANICS OF THE HOUSEHOLD 

Intercommunicating Telephones. — Furnish and install an intercom- 
municating telephone system complete with all telephone sets, wiring, 
batteries, etc. All wires to be cables containing one pair of No. 22 B. & S. 
gage conductors for each station and a pair of No. 16 B. & S. gage conductors 
for talking and ringing battery respectively. Each pair of wires shall be 
twisted and all pairs shall be twisted around each other to eliminate cross 
talk and inductive noises. The wires shall be silk insulated, with a moisture 
repellent of beeswax or varnish and the whole covered with a lead sheath 
at least 3^^4 inch in thickness. Where cables terminate in outlet boxes they 
shall be fanned out and laced in an orderly manner and secured to connect- 
ing terminals, one of which shall be provided for each wire. Install where 
directed in an approved cabinet at least four cells of dry battery each, for 
talking and ringing purposes. 

Installation of Interphone Cable. — Intercommunicating cables 
shall be supported with pipe straps and liberal clearance shall be observed 
where near steam or other pipes. 

Automatic Door Switch. — Where indicated on the plan, clothes 
closets shall be equipped with automatic door 
switch to connect the light when the door is open. 
Fig. 266 is placed in the door frame in such 
position that electric contact is made by release of 
the projecting pin as the door is opened. When 
the door is closed, the pin is depressed and the light 
is extinguished 

Plug Receptacles. — Plug receptacles shall be 
selected from the styles shown in Figs. 267, a, h, c 
or d, , 

Fig. 266.-— pjg 267,a is the disappearing-door type with 

A. U t O HI SL ti 1 C 1111 1 n • 1 ^ i ~ 

door switch. bevcled-edge brass cover plate finished to match 
surrounding hardware. In this receptacle the doors 
are pushed inward by the insertion of the plug and upon its 
withdrawal close automatically, effectually excluding dirt and 
concealing the live terminals. It is the latest and best plug re- 
ceptacle obtainable. 

Fig. 267,6 is of the Chapman type with beveled-edge brass 
cover plate finished to match surrounding hardware. In this 
receptacle the doors open outward but are fiush whether the plug 
is in or out. 

Fig. 267, c is of the screw-plug type with beveled-edge brass 
cover plate finished to match surrounding hardware. By many 




ELECTRICITY 



379 




Fig. 267. — Styles of plug receptacles. 




^^> (d) 

Fig. 268. — Heating-device receptacles. 



380 



MECHANICS OF THE HOUSEHOLD 



this is preferred for apartment use as it will receive any style of 
Edison attachment plug. 

Fig. 267,d is of the removable-mechanism type with beveled- 
edge brass cover plate finished to match surrounding hardware. 




Fig. 269. — Service switches. 



The mechanism of this receptacle is exchangeable with the mech- 
anism of the double-pole switch as shown in Fig. 270,c. 

Heater Switch, Pilot' and Receptacle. — Heating-device out- 
lets shall be equipped with combination of switch, pilot light and 




(e) W^ (f)" 

Fig. 270. — Local wall switches. 

receptacle with plug and spare pilot lamp. Figs. 268,a, b, c and 
d, represent various forms from which selection may be made. 
All are adapted for the same purpose and differ only in mechan- 
ical arrangement. 



ELECTRICITY 



381 



Service Switch. — The service entrance switch may be selected 
from the three styles shown in Figs. 269, a, 6, and c. 




(a) (b) 

Fig. 271.— Pilot lights. 




(^) (d) 

Fig. 272. — Wall and ceiling sockets. 

Fig. 269,a is composed of a 30-ampere porcelain base with con- 
nections for plug fuses. 

Fig. 269,6 is a slate base with connections for cartridge fuses. 



382 



MECHANICS OF THE HOUSEHOLD 



Fig. 269,c is a slate base with connections for open-link fuses. 

Local Switches. — ^Local wall switches may be selected from the 
various styles shown in Figs. 270,a, h, c, d and e. 

Fig. 270, a is the two-button flush type completely enclosed in a 
box of non-breakable insulating material with brass beveled 
cover plate finished to match surrounding hardware. 




^'^ <^) (2) 

Fig. 273. — Drop-light attachments and lamp bases. 

Fig. 270, & is a two-button flush type with brass beveled-edge 
cover plate finished to match surrounding hardware. 

Fig. 270, c is of the removable-mechanism type with brass bev- 
eled-edge cover plate finished to match surrounding hardware. 

Fig. 270,d is the single-button flush type with brass beveled- 
edge cover plate finished to match surrounding hardware. 

Fig. 270,6 is the rotary-flush type with brass beveled-edge 
cover plate finished to match surrounding hardware. 



ELECTRICITY 383 

Pilot Lights. — Switches controlhng cellar, attic and porch 
lights may be either Fig. 270,a or b. 

Fig. 270,a requires for its installation a two-gang outlet box. 
The ruby bulPs-eye which covers the lamp is practically flush, 
extending from the wall no further than the buttons of the 
switch. 

Fig. 270, & is installed in a single-gang box. The lamp ex- 
tends through the plate and is protected by a perforated cage 
which extends about an inch from the plate. 

Wall and Ceiling Sockets. — One-light ceiling receptacles may 
be selected from the types shown in Figs. 272,a, b, c, d and e. 

Fig. 272, a is of a type to fit standard 33<^-inch or 4-inch 
outlet boxes. 

Fig. 272 jb is of the small concealed-base type. 

Fig. 272, c is of the large concealed-base type. 

Fig. 272 jd is of the insulated-base type. 

Fig. 272, e is of the porcelain-base type. 

Sockets in cellars shall be made entirely of porcelain. Those 
in bathrooms shall be entirely of porcelain and of the pull type. 

Drop Lights. — Drop lights shall consist of the necessary 
length of reinforced cord supported by either brass or porcelain 
bases. Each drop cord to have an adjuster. Figs. 273, a, 6, c, d, 6, 
/, gf, illustrate the various styles. Fig. 273, /i is a shade holder to 
be used with the drop lights. 



INDEX 



Acetylene, gas burner, 302 

gas machine, the Colt, 300 

machines, 295 
generators, types of, 297 
stoves, 304 
Air conditioning, 240 
cooling plants, 244 
discharged by a flue, 225 
eliminators, 35, 36 
properties of, table, 199 
tester, the Wolpert, 233 
valves, 19 
Alcohol, sad irons, 289 

table stoves, 293 
Annunciators, 346 
Anthracite, graphitic, 186 
Atmospheric humidity, 196 

B 

Backventing, of plumbing, 105 
Bathroom, 97 
Bathtubs, 98 

fixtures for, 100 
Bibb, compression flange, 89 

flange, 89 

Fuller, 89 

hose, 89 

lever handle, 90 

screw, 89 

self-closing, 90 

solder, 89 

wash-tray, 91 
Boiler, at end of season, 79 

cast-iron, 19, 20, 38 

cylindrical form of, 38 

house heating, 19, 24 

rules for management of, 77 

sheet-metal, 19 



Boiler, steam, rules for management 
of, 78 

the house-heating steam, 19 
Boyles' law, definition, 161, 272 
Briquettes, 189 
British thermal units, 4 

for one cent, 190 
B.t.u., 2, 32, 182, 185 
Burglar alarms, 344 
Buzzers, 344 

C i 

Candle, foot, 313 

Hefner, 310 

power, 310 

horizontal, 310 
spherical, 311 
Cellar drain, 84 

Cell, Pilot, storage battery, 370 
Cesspools, 169 
Charcoal, 188 
Check-draft damper, 24 
Chimney flue, the right, 79 
Chimneys, ^'smokey,'' 80, 81 
Cisterns, filters for, 152, 153 

galvanized iron tanks as, 152 

rain-water, 151 

wooden, 152 
Clinkers, 72, 73 
Close-nipples, 28 
Coal, 182 

anthracite or hard, 183, 193 

bituminous or soft, 184 

burning soft, 75 

calorific value of typical Ameri- 
can, 192, 193 

cannel, 186 

coking, 184 

comparative value of, 189 

free burning, 75 



385 



386 



INDEX 



Coal, fusing-coking, 75 

grades of soft, 184 

pea size, 76 

price of, 190, 191 

semi-bituminous, 186, 193 
Cocks, basin, 92 

bibb, 88 

corporation, 87 

curb, 87 

Fuller, 91 
bibb, 89 
repairs for, 91 

pantry, 93 

sill, 93 

stop and drain, 88 

stop and waste, 87 
Code, national electric, 371 
Coke, 76, 188 

gas, 188 
Column, the water, 22 
Condensation, water of, 6, 10, 11, 

15, 35 
Conductors, 374 
Cord, lamp, 363 

portable, 363 
Current, alternating, 332 

direct, 332 



Damper, ash-pit, 59 

check-draft, 24, 67, 69, 70 

direct-draft, 59, 61, 67 

regulator, 59, 60 

combined thermostat and, 67 
for hot-water furnaces, 61, 62 
for steam boiler, 60, 78 
Design, heating plant, 44 
Devining rod, 137 
Dew-point, 209 

to determine the, 212 
Dim-a-lite, 323 
Door bells, 342 
Draft, economy of good furnace, 70 

hand, regulation, 59 

induced, 69 
Drip-cock, 23 



Dry cells, 354 



E 



Electric annunciators, 346 

batteries, 354 

battery formation, 358 
testers, 360 

burglar alarms, 344 

buzzers, 344 

conductors, 362 

door bell, 342 

dry cell, 355 

flat-iron, 326 

fuse plugs, 334, 337 

generating plants, 363 

heaters, 338 

heating devices, 305 

lamp cord, 362 

lamps. Gem, 306 
incandescent, 306 

motors, 332 

panel, 336 

range, 340 

signals, 341 

stoves, 339 

table pushes, 346 

toaster, 330 
Electrical measurements, units of, 317 
Electricity, 305 
Eliminator, air, 35, 36 
Evaporation as a cooling agent, 243 



Filaments, carbon, 308 

incandescent lamp, 306, 307 

tungsten, 307 
Fire-box, 19, 20, 54 
Firing, first day, 73 

in moderate weather, 74 

in severe weather, 74 

night, 72 
Fixtures, bathroom, 105 

kitchen and laundry, 94 
Flat-iron, electric, 326 
Flues, furnace, 55 



INDEX 



387 



Flush tanks, 110 

details of construction, 112, 113 
low down, 111 
Foot-candle, 313 
Frost prediction, 212 
Fuels, comparative value of coal 
to other, 189 
danger from gaseous and liquid, 

294 
heating values of domestic, 252 
moisture in, 194 
Furnace, cast-iron, 54 

firing, general rules for, 70 

times of day for, 72 
location of, 54 
the hot-air, 51, 52 
construction of, 52 
Furnace-gas leaks, 54 
Fuse plugs, 334 



Gage, Bourdon type of, 23 

electrified Bourdon spring pres- 
sure, 36 

glass, 22, 40, 161, 162 

steam, 22 

water, 22 
Gas, acetylene, machines, 295 

all-oil water, 251 

blau, 251 

burner, Bunsen, 275 
open-flame, 278 

coal, 250 

lamps, mantle, 274, 276, 277 

lighters, 302 

measurements of, 253 

meter dials, reading of, 255, 256 

meters, 254 

prepayment, 256 

Pintsch, 251 

service rules, 256, 257 

ranges, 258 

water, 251 
Gases, heating values of, 252 
Gasoline, 250 

Beaume test of, 261 



Gasoline, boulevard lamp, 287 

central generator plants for use 

of, 282 
cold process system of lighting 

with, 264, 265 
gas lamps, 286 
gravity test of, 262 
hollow-wire system of lighting 

and heating with, 269 
lamps, inverted mantle, 279 

portable, 280, 281 
lighting and heating with, 259, 

264 
regulation and sale of, 261 
sad irons, 289 
stoves, burners for, 288 
Gate valve, 94 
Globe valve, 93 

angle, 94 
Grate surface, 53 
Gravity system, low pressure, 6, 15 



H 



Heaters, combination hot-air and 

hot-water, 56 
direct and indirect, 28 
furnace hot-water, 122^ 
instantaneous, 123 
tank, 121 
wash boilers, 96 
Heating, C. A. Dunham's system of 

vapor, 34, 35 
direct indirect, 30 
hot-water, 26 
indirect method of, 29, 30 
low pressure system of, 5, 6 
overhead or drop system of 

steam, 14 
system of hot water, 44 
plants, management of, 70 
separate return system of 

steam, 13 
single pipe system of steam, 

6, 12, 15 
steam, 26 
surface of furnaces, 56 



388 



INDEX 



Heating, radiators, 26 

two pipe system of steam, 6, 10, 
11, 15 
Heat, of vaporization, 2 

specific, 37 
Hot-air furnace, 61 
Hot-water heaters, 38 
House drain, 82 
Humidifying apparatus, 215 

plants, 242 
Humidity, absolute, 196 

atmospheric, 196 

control, 244 

of the air, 196 

relative, 197, 204 
Hydraulic ram, 154 

double acting, 157 

single acting, 155 
Hydrometer, storage battery, 368 
Hygrodeik, 206 
Hygrometer, 204 

dial, 208 



Illumination, 313 
intensity of, 314 
quantity of, 314 



K 

Kerosene, 263 

legal tests for, 263 



Lamp, base, the Edison, 311 
cord, 363 
labels, 312 

Lamps, boulevard, 287 
carbon filament, 311 
central-generator gas, 286 
daylight, electric, 324 
gas-filled electric, 324 
incandescent electric, 306 

mantle, 276 
inverted-mantle gasoline, 279 



Lamps, Mazda, 310 

miniature electric, 320, 325 

portable, gasoline, 280 

tantalum, 306 

tungsten-filament, 306 

turn-down electric, 321 
Lights, drop, 383 

flash, 326 

pilot, 383 
Lignite, 186 
Lumen, 313 

O 

Outlet boxes, 373 
Overflow pipe, 45 
Overheated water, 47 



Peat, 187 
Pilot Hght, 375 
Pipes, covering, 33 

eliminator, 36 

flow, 57 

openings stopped, 113 

overflow, 40, 41 

return, 6, 10, 57 

supply, 6, 10 
Plant, hot-water heating, 37 

steam heating, 1, 5 
Plug receptacles, 378 
Plumbers friend, 113 
Plumbing, 81 

rough, 82 
Pneumatic motor valve, 237 

radiator valve, 237 
PoUuted water, 134 
Pollution of wells, 134 
Pressure, absolute, 4 

gage, 4 

tank, 162 

vapor, 35, 36 
Properties of steam, 3 
Psychrometer, 207 
Pump, force, the, 146 

lift, the, 144 

tank, 146 



INDEX 



389 



Pumps, 144 
chain, 151 

deep well, 150 ' 

for driven wells, 150 
priming of, 145 
well, 148 
wooden, 148 

R 

Radiating surface, 1, 21, 22, 27 
Radiators, air vent on, 77 

connections, 10, 47 

corner, 28 

finishings, 31 

forms of, 26 

hot-water, 28, 49 

rules for proportioning, 24, 25 

single column, 28 
pipe, 10, 15 

three column, 28 

to control, 79 

wall, 28 

water-filled, 15 
Range boilers, 115 

blow-off cock, 118 

double heater connections for, 
119 

excessive pressure in, 117 

horizontal, 119 

location, 118 
Reflectors, 315 

choice of, 316 ; 

focusing, 316 

holoplane, 3^15 

intensive, 316 
Registers, rules for proportioning, 55 
Regulator, combined thermostat and 
damper, 67 

damper, 59, 60, 67 

draft, 24 

temperature, 59, 67 
Riser, 6, 10 

S 

Sad irons, alcohol, 292 
gasoline, 289 



Safety valve, 24, 44, 47, 67 
Septic tank, 170 

and anaerobic filter, 174 

automatic siphon for, 176 

concrete, 179 

limit of efficiency of, 178 

Universal Portland Cement Co., 
179 

with sand-bed filter, 171 
Sewage, 168 

disposal, 168 

purification, 168 
Sewer, 82, 85 

gas, 114 
Short circuiting, 334 
Sitz bath, 98 
Slicing bar, 72 
Slugging, 15 
Soil pipe, 84, 107 
Soot pocket, 80 
Stand pipe eliminator, 36 
Steam temperatures, 4 
Stop-cock, 46 
Stove, acetylene, 292 

gasoline, 288 

putty, 54 
Surface, grate, 53 

air-heating, 53 
Surging, 15 
Switch, automatic door, 378 

heater, 380 

local, 382 

service, 381 
System, high-pressure hot-water, 41 

low-pressure gravity, 6 
hot-water, 38 

overhead or drop, 14 

separate return, 13 

single pipe, 8 

two pipe, 10 



Table, air discharged from flues, 229 
required for ventilation, 220 
calorific value of American 
coals, 192 



390 



INDEX 



Table, dew-point, 210, 211 
frost prediction, 214 
heating values of coals, 93 
gases, 252 
wood, 187, 188 
hot-air furnaces, 51 

registers, 51 
lumens per watt, 314 
prices of fuels, 191 
properties of air, 199 

steam, 3 
radiators, sizes of, 27 
record of evaporation from hot- 
air furnace, 217 
relative heating values of do- 
mestic fuel, 252 
humidity, 202, 203 
sizes of hard coal, 183 
heating mains, 26 
hot-air furnaces, 51 
soft coal, 184 
thermal units for one cent, 190 
Table pushes, 346 
Tank heaters, 121 

expansion, 38, 40, 41, 45, 46, 47 
Telephones, intercommuni eating, 

340 
Temperature regulation, 59 
hand, 59 
pneumatic, 234 
Thermostats, 62, 67 
controllers, 62, 63 
electric, 62 
motor, 64 
National Regulator Co., 235, 

236 
pneumatic, 62 
time attachment, 63 
Transformers, bell-ringing, 347 

lamp, 316 
Traps, Bower, 103 
clean sweep, 103 
drum, 103, 105 

for bathroom fixture, 102, 103 ] 
inside, 83 

non-siphoning, 105 
outside, 83 



Traps, sewer for house drains, 82 

siphoning, 106 

S, 103, 104 
Try-cocks, 22, 23 
Tungsten, 307 



U 



Union joint, 18 



Vacuum, 5 
Valve, air, 79 

angle, 18 

check, 42, 43 

definition of, 88, 93 

disc, 19 

gjobe, 93 

hot-water radiator, 49 

Ohio hot-water, 49 

on cellar mains, 78 

safety, 24, 44, 47 

steam radiator, 18 

stem, 19 
Valves, definition of, 93 

globe, 93 
Vaporization, heat of, 2 
Ventilation, 219 

apparatus, 239 

by direct method of heating, 31 

by indirect method of heating, 
31 

cost of, 230 

DeChaumont standard of, 219 

mechanical, 237 

of dwellings, 222, 223, 224 

Plenum method of, 239 

quantity of air required for, 220 
Vents, air, 16, 45, 48, 49 

automatic air, 16 
hot-water air, 50 

Monash No. 16 air, 16 

pipe, 83 

radiator, 16 

sewer, 85 

the Allen float, 16 



INDEX 



391 



Voltage variation, effect of, 321 

W 

Wash stands and lavatories, 101 
Waste stack, 84, 85 
Water, ammonia in, 130 
analyses, 126 
artesian, 128 
back, 115 
chlorine in, 133 
closets, 108 
siphon-jet, 108 
washdown, 109 
washout, 108 
frost, 115 
hammer, 9, 15 
hardness in, 131 
iron in, 131 
lift, 165 
medical, 128 
of condensation, 11 
organic matter in, 130 
overheated, 121 
Pokegama, 127 
polluted, 133 
river, 127 
seal, 83 

softening with hydrated sili- 
cates, 132 
supply, 87, 125 

electric power, 164 
plants, domestic, 158 
gravity, 158 



Water, power, 163 

pressure tank system of, 160 
wind power, 164 
table, 137 
Wattmeter, periodic tests of, 354 

readings, 352 

recording, 350 

state regulation of, 353 

to read the, 350 
Well, the ideal, 140 
Wells, artesian, 140 

bored, 141 

breathing, 143 

cleaning of, 142 

concrete coverings for, 140 

construction of, 138 

curbing of, 136, 140 

cylinders for tubular, 151 

driven, 141 

dug, 139 

flowing, 138 

freezing, 144 

gases in, 142 

open, 139 

peculiarities of, 143 

safe distance in the location of, 
135 

selection of the type of, 138 

surface pollution of, 135 
Wiped joints, 107 
Wire annunciator, 353 
Wiring, electric light, 372 
Wood, 187 

heating value of, 187 



